diff --git a/doc/talks/io2010/eval1.go b/doc/talks/io2010/eval1.go
index 2d7fc3be6c4..582f43e8ea2 100644
--- a/doc/talks/io2010/eval1.go
+++ b/doc/talks/io2010/eval1.go
@@ -101,7 +101,6 @@ func main() {
 	}
 }
 
-
 // Custom grammar and values
 
 var precTab = map[string]int{
@@ -125,7 +124,7 @@ func newVal(lit string) Value {
 	if err == nil {
 		return Int(x)
 	}
-	b, err := strconv.Atob(lit)
+	b, err := strconv.ParseBool(lit)
 	if err == nil {
 		return Bool(b)
 	}
@@ -175,7 +174,7 @@ func (x Int) BinaryOp(op string, y Value) Value {
 
 type Bool bool
 
-func (x Bool) String() string { return strconv.Btoa(bool(x)) }
+func (x Bool) String() string { return strconv.FormatBool(bool(x)) }
 func (x Bool) BinaryOp(op string, y Value) Value {
 	switch y := y.(type) {
 	case Error:
@@ -195,7 +194,6 @@ func (x Bool) BinaryOp(op string, y Value) Value {
 	return Error(fmt.Sprintf("illegal operation: '%v %s %v'", x, op, y))
 }
 
-
 func trace(newVal func(string) Value) func(string) Value {
 	return func(s string) Value {
 		v := newVal(s)
diff --git a/doc/talks/io2010/eval2.go b/doc/talks/io2010/eval2.go
index 5524c8b3aa9..6f826e12d09 100644
--- a/doc/talks/io2010/eval2.go
+++ b/doc/talks/io2010/eval2.go
@@ -101,7 +101,6 @@ func main() {
 	}
 }
 
-
 // Custom grammar and values
 
 var precTab = map[string]int{
@@ -125,7 +124,7 @@ func newVal(lit string) Value {
 	if err == nil {
 		return Int(x)
 	}
-	b, err := strconv.Atob(lit)
+	b, err := strconv.ParseBool(lit)
 	if err == nil {
 		return Bool(b)
 	}
@@ -184,7 +183,7 @@ func (x Int) BinaryOp(op string, y Value) Value {
 
 type Bool bool
 
-func (x Bool) String() string { return strconv.Btoa(bool(x)) }
+func (x Bool) String() string { return strconv.FormatBool(bool(x)) }
 func (x Bool) BinaryOp(op string, y Value) Value {
 	switch y := y.(type) {
 	case Error:
@@ -227,7 +226,6 @@ func (x String) BinaryOp(op string, y Value) Value {
 	return Error(fmt.Sprintf("illegal operation: '%v %s %v'", x, op, y))
 }
 
-
 func trace(newVal func(string) Value) func(string) Value {
 	return func(s string) Value {
 		v := newVal(s)
diff --git a/misc/cgo/stdio/fib.go b/misc/cgo/stdio/fib.go
index c02e31fd8d8..431d9cefee7 100644
--- a/misc/cgo/stdio/fib.go
+++ b/misc/cgo/stdio/fib.go
@@ -26,7 +26,7 @@ func fibber(c, out chan int64, i int64) {
 	}
 	for {
 		j := <-c
-		stdio.Stdout.WriteString(strconv.Itoa64(j) + "\n")
+		stdio.Stdout.WriteString(strconv.FormatInt(j, 10) + "\n")
 		out <- j
 		<-out
 		i += j
diff --git a/misc/dashboard/builder/http.go b/misc/dashboard/builder/http.go
index 9de54a36947..0f26059948a 100644
--- a/misc/dashboard/builder/http.go
+++ b/misc/dashboard/builder/http.go
@@ -134,7 +134,7 @@ func (b *Builder) updatePackage(pkg string, ok bool, buildLog, info string) erro
 		"builder": b.name,
 		"key":     b.key,
 		"path":    pkg,
-		"ok":      strconv.Btoa(ok),
+		"ok":      strconv.FormatBool(ok),
 		"log":     buildLog,
 		"info":    info,
 	})
diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index 20cac1944b7..646857419d4 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -355,7 +355,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 				// with enum-derived constants.  Otherwise
 				// in the cgo -godefs output half the constants
 				// are in hex and half are in whatever the #define used.
-				i, err := strconv.Btoi64(n.Define, 0)
+				i, err := strconv.ParseInt(n.Define, 0, 64)
 				if err == nil {
 					n.Const = fmt.Sprintf("%#x", i)
 				} else {
@@ -1333,7 +1333,7 @@ func (c *typeConv) Opaque(n int64) ast.Expr {
 func (c *typeConv) intExpr(n int64) ast.Expr {
 	return &ast.BasicLit{
 		Kind:  token.INT,
-		Value: strconv.Itoa64(n),
+		Value: strconv.FormatInt(n, 10),
 	}
 }
 
diff --git a/src/cmd/goinstall/download.go b/src/cmd/goinstall/download.go
index 7c5382a3c44..2147e62f08f 100644
--- a/src/cmd/goinstall/download.go
+++ b/src/cmd/goinstall/download.go
@@ -489,7 +489,7 @@ func selectTag(goVersion string, tags []string) (match string) {
 	const rPrefix = "release.r"
 	if strings.HasPrefix(goVersion, rPrefix) {
 		p := "go.r"
-		v, err := strconv.Atof64(goVersion[len(rPrefix):])
+		v, err := strconv.ParseFloat(goVersion[len(rPrefix):], 64)
 		if err != nil {
 			return ""
 		}
@@ -498,7 +498,7 @@ func selectTag(goVersion string, tags []string) (match string) {
 			if !strings.HasPrefix(t, p) {
 				continue
 			}
-			tf, err := strconv.Atof64(t[len(p):])
+			tf, err := strconv.ParseFloat(t[len(p):], 64)
 			if err != nil {
 				continue
 			}
diff --git a/src/cmd/gotest/flag.go b/src/cmd/gotest/flag.go
index 0e7c619df42..b0b0cae5cc9 100644
--- a/src/cmd/gotest/flag.go
+++ b/src/cmd/gotest/flag.go
@@ -156,7 +156,7 @@ func flag(i int) (f *flagSpec, value string, extra bool) {
 
 // setBoolFlag sets the addressed boolean to the value.
 func setBoolFlag(flag *bool, value string) {
-	x, err := strconv.Atob(value)
+	x, err := strconv.ParseBool(value)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "gotest: illegal bool flag value %s\n", value)
 		usage()
diff --git a/src/pkg/archive/tar/reader.go b/src/pkg/archive/tar/reader.go
index 76955e2ec03..13fe2700f9b 100644
--- a/src/pkg/archive/tar/reader.go
+++ b/src/pkg/archive/tar/reader.go
@@ -80,7 +80,7 @@ func (tr *Reader) octal(b []byte) int64 {
 	for len(b) > 0 && (b[len(b)-1] == ' ' || b[len(b)-1] == '\x00') {
 		b = b[0 : len(b)-1]
 	}
-	x, err := strconv.Btoui64(cString(b), 8)
+	x, err := strconv.ParseUint(cString(b), 8, 64)
 	if err != nil {
 		tr.err = err
 	}
diff --git a/src/pkg/archive/tar/writer.go b/src/pkg/archive/tar/writer.go
index b9310b3f189..d35726bf9d8 100644
--- a/src/pkg/archive/tar/writer.go
+++ b/src/pkg/archive/tar/writer.go
@@ -79,7 +79,7 @@ func (tw *Writer) cString(b []byte, s string) {
 
 // Encode x as an octal ASCII string and write it into b with leading zeros.
 func (tw *Writer) octal(b []byte, x int64) {
-	s := strconv.Itob64(x, 8)
+	s := strconv.FormatInt(x, 8)
 	// leading zeros, but leave room for a NUL.
 	for len(s)+1 < len(b) {
 		s = "0" + s
@@ -90,7 +90,7 @@ func (tw *Writer) octal(b []byte, x int64) {
 // Write x into b, either as octal or as binary (GNUtar/star extension).
 func (tw *Writer) numeric(b []byte, x int64) {
 	// Try octal first.
-	s := strconv.Itob64(x, 8)
+	s := strconv.FormatInt(x, 8)
 	if len(s) < len(b) {
 		tw.octal(b, x)
 		return
diff --git a/src/pkg/compress/flate/huffman_bit_writer.go b/src/pkg/compress/flate/huffman_bit_writer.go
index efd99c6b954..8d0b4f9c1e8 100644
--- a/src/pkg/compress/flate/huffman_bit_writer.go
+++ b/src/pkg/compress/flate/huffman_bit_writer.go
@@ -106,8 +106,8 @@ func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
 }
 
 func (err WrongValueError) Error() string {
-	return "huffmanBitWriter: " + err.name + " should belong to [" + strconv.Itoa64(int64(err.from)) + ";" +
-		strconv.Itoa64(int64(err.to)) + "] but actual value is " + strconv.Itoa64(int64(err.value))
+	return "huffmanBitWriter: " + err.name + " should belong to [" + strconv.FormatInt(int64(err.from), 10) + ";" +
+		strconv.FormatInt(int64(err.to), 10) + "] but actual value is " + strconv.FormatInt(int64(err.value), 10)
 }
 
 func (w *huffmanBitWriter) flushBits() {
diff --git a/src/pkg/compress/flate/inflate.go b/src/pkg/compress/flate/inflate.go
index 3f0c94864a4..3f2042bfe92 100644
--- a/src/pkg/compress/flate/inflate.go
+++ b/src/pkg/compress/flate/inflate.go
@@ -25,7 +25,7 @@ const (
 type CorruptInputError int64
 
 func (e CorruptInputError) Error() string {
-	return "flate: corrupt input before offset " + strconv.Itoa64(int64(e))
+	return "flate: corrupt input before offset " + strconv.FormatInt(int64(e), 10)
 }
 
 // An InternalError reports an error in the flate code itself.
@@ -40,7 +40,7 @@ type ReadError struct {
 }
 
 func (e *ReadError) Error() string {
-	return "flate: read error at offset " + strconv.Itoa64(e.Offset) + ": " + e.Err.Error()
+	return "flate: read error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
 }
 
 // A WriteError reports an error encountered while writing output.
@@ -50,7 +50,7 @@ type WriteError struct {
 }
 
 func (e *WriteError) Error() string {
-	return "flate: write error at offset " + strconv.Itoa64(e.Offset) + ": " + e.Err.Error()
+	return "flate: write error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
 }
 
 // Huffman decoder is based on
diff --git a/src/pkg/crypto/openpgp/write.go b/src/pkg/crypto/openpgp/write.go
index 60dae01e64b..bdee57d767c 100644
--- a/src/pkg/crypto/openpgp/write.go
+++ b/src/pkg/crypto/openpgp/write.go
@@ -183,7 +183,7 @@ func Encrypt(ciphertext io.Writer, to []*Entity, signed *Entity, hints *FileHint
 	for i := range to {
 		encryptKeys[i] = to[i].encryptionKey()
 		if encryptKeys[i].PublicKey == nil {
-			return nil, error_.InvalidArgumentError("cannot encrypt a message to key id " + strconv.Uitob64(to[i].PrimaryKey.KeyId, 16) + " because it has no encryption keys")
+			return nil, error_.InvalidArgumentError("cannot encrypt a message to key id " + strconv.FormatUint(to[i].PrimaryKey.KeyId, 16) + " because it has no encryption keys")
 		}
 
 		sig := to[i].primaryIdentity().SelfSignature
diff --git a/src/pkg/crypto/tls/handshake_server_test.go b/src/pkg/crypto/tls/handshake_server_test.go
index e00c32c5508..d98e13decf6 100644
--- a/src/pkg/crypto/tls/handshake_server_test.go
+++ b/src/pkg/crypto/tls/handshake_server_test.go
@@ -159,7 +159,7 @@ func TestHandshakeServerSSLv3(t *testing.T) {
 
 var serve = flag.Bool("serve", false, "run a TLS server on :10443")
 var testCipherSuites = flag.String("ciphersuites",
-	"0x"+strconv.Itob(int(TLS_RSA_WITH_RC4_128_SHA), 16),
+	"0x"+strconv.FormatInt(int64(TLS_RSA_WITH_RC4_128_SHA), 16),
 	"cipher suites to accept in serving mode")
 
 func TestRunServer(t *testing.T) {
@@ -170,7 +170,7 @@ func TestRunServer(t *testing.T) {
 	suites := strings.Split(*testCipherSuites, ",")
 	testConfig.CipherSuites = make([]uint16, len(suites))
 	for i := range suites {
-		suite, err := strconv.Btoui64(suites[i], 0)
+		suite, err := strconv.ParseUint(suites[i], 0, 64)
 		if err != nil {
 			panic(err)
 		}
diff --git a/src/pkg/debug/dwarf/buf.go b/src/pkg/debug/dwarf/buf.go
index 6b4af7d53dc..6dc28d2568c 100644
--- a/src/pkg/debug/dwarf/buf.go
+++ b/src/pkg/debug/dwarf/buf.go
@@ -149,5 +149,5 @@ type DecodeError struct {
 }
 
 func (e DecodeError) Error() string {
-	return "decoding dwarf section " + e.Name + " at offset 0x" + strconv.Itob64(int64(e.Offset), 16) + ": " + e.Err
+	return "decoding dwarf section " + e.Name + " at offset 0x" + strconv.FormatInt(int64(e.Offset), 16) + ": " + e.Err
 }
diff --git a/src/pkg/debug/dwarf/const.go b/src/pkg/debug/dwarf/const.go
index 1a3fec155c2..918b153d078 100644
--- a/src/pkg/debug/dwarf/const.go
+++ b/src/pkg/debug/dwarf/const.go
@@ -178,7 +178,7 @@ func (a Attr) GoString() string {
 			return "dwarf.Attr" + s
 		}
 	}
-	return "dwarf.Attr(" + strconv.Itoa64(int64(a)) + ")"
+	return "dwarf.Attr(" + strconv.FormatInt(int64(a), 10) + ")"
 }
 
 // A format is a DWARF data encoding format.
@@ -347,7 +347,7 @@ func (t Tag) GoString() string {
 			return "dwarf.Tag" + s
 		}
 	}
-	return "dwarf.Tag(" + strconv.Itoa64(int64(t)) + ")"
+	return "dwarf.Tag(" + strconv.FormatInt(int64(t), 10) + ")"
 }
 
 // Location expression operators.
diff --git a/src/pkg/debug/dwarf/type.go b/src/pkg/debug/dwarf/type.go
index e8ce8d57b8c..9be66658fe9 100644
--- a/src/pkg/debug/dwarf/type.go
+++ b/src/pkg/debug/dwarf/type.go
@@ -110,7 +110,7 @@ type ArrayType struct {
 }
 
 func (t *ArrayType) String() string {
-	return "[" + strconv.Itoa64(t.Count) + "]" + t.Type.String()
+	return "[" + strconv.FormatInt(t.Count, 10) + "]" + t.Type.String()
 }
 
 func (t *ArrayType) Size() int64 { return t.Count * t.Type.Size() }
@@ -171,10 +171,10 @@ func (t *StructType) Defn() string {
 			s += "; "
 		}
 		s += f.Name + " " + f.Type.String()
-		s += "@" + strconv.Itoa64(f.ByteOffset)
+		s += "@" + strconv.FormatInt(f.ByteOffset, 10)
 		if f.BitSize > 0 {
-			s += " : " + strconv.Itoa64(f.BitSize)
-			s += "@" + strconv.Itoa64(f.BitOffset)
+			s += " : " + strconv.FormatInt(f.BitSize, 10)
+			s += "@" + strconv.FormatInt(f.BitOffset, 10)
 		}
 	}
 	s += "}"
@@ -206,7 +206,7 @@ func (t *EnumType) String() string {
 		if i > 0 {
 			s += "; "
 		}
-		s += v.Name + "=" + strconv.Itoa64(v.Val)
+		s += v.Name + "=" + strconv.FormatInt(v.Val, 10)
 	}
 	s += "}"
 	return s
diff --git a/src/pkg/debug/elf/elf.go b/src/pkg/debug/elf/elf.go
index c71b230bd95..03e42b03465 100644
--- a/src/pkg/debug/elf/elf.go
+++ b/src/pkg/debug/elf/elf.go
@@ -1490,11 +1490,11 @@ func stringName(i uint32, names []intName, goSyntax bool) string {
 			if goSyntax {
 				s = "elf." + s
 			}
-			return s + "+" + strconv.Uitoa64(uint64(i-n.i))
+			return s + "+" + strconv.FormatUint(uint64(i-n.i), 10)
 		}
 	}
 
-	return strconv.Uitoa64(uint64(i))
+	return strconv.FormatUint(uint64(i), 10)
 }
 
 func flagName(i uint32, names []intName, goSyntax bool) string {
@@ -1512,10 +1512,10 @@ func flagName(i uint32, names []intName, goSyntax bool) string {
 		}
 	}
 	if len(s) == 0 {
-		return "0x" + strconv.Uitob64(uint64(i), 16)
+		return "0x" + strconv.FormatUint(uint64(i), 16)
 	}
 	if i != 0 {
-		s += "+0x" + strconv.Uitob64(uint64(i), 16)
+		s += "+0x" + strconv.FormatUint(uint64(i), 16)
 	}
 	return s
 }
diff --git a/src/pkg/debug/macho/macho.go b/src/pkg/debug/macho/macho.go
index 1386f5acf57..bc14226c565 100644
--- a/src/pkg/debug/macho/macho.go
+++ b/src/pkg/debug/macho/macho.go
@@ -278,7 +278,7 @@ func stringName(i uint32, names []intName, goSyntax bool) string {
 			return n.s
 		}
 	}
-	return strconv.Uitoa64(uint64(i))
+	return strconv.FormatUint(uint64(i), 10)
 }
 
 func flagName(i uint32, names []intName, goSyntax bool) string {
@@ -296,10 +296,10 @@ func flagName(i uint32, names []intName, goSyntax bool) string {
 		}
 	}
 	if len(s) == 0 {
-		return "0x" + strconv.Uitob64(uint64(i), 16)
+		return "0x" + strconv.FormatUint(uint64(i), 16)
 	}
 	if i != 0 {
-		s += "+0x" + strconv.Uitob64(uint64(i), 16)
+		s += "+0x" + strconv.FormatUint(uint64(i), 16)
 	}
 	return s
 }
diff --git a/src/pkg/encoding/ascii85/ascii85.go b/src/pkg/encoding/ascii85/ascii85.go
index 6f592f3d727..7d004b5e5d7 100644
--- a/src/pkg/encoding/ascii85/ascii85.go
+++ b/src/pkg/encoding/ascii85/ascii85.go
@@ -168,7 +168,7 @@ func (e *encoder) Close() error {
 type CorruptInputError int64
 
 func (e CorruptInputError) Error() string {
-	return "illegal ascii85 data at input byte " + strconv.Itoa64(int64(e))
+	return "illegal ascii85 data at input byte " + strconv.FormatInt(int64(e), 10)
 }
 
 // Decode decodes src into dst, returning both the number
diff --git a/src/pkg/encoding/asn1/common.go b/src/pkg/encoding/asn1/common.go
index 01f4f7b6ec7..f7cb3acbb86 100644
--- a/src/pkg/encoding/asn1/common.go
+++ b/src/pkg/encoding/asn1/common.go
@@ -98,7 +98,7 @@ func parseFieldParameters(str string) (ret fieldParameters) {
 		case part == "printable":
 			ret.stringType = tagPrintableString
 		case strings.HasPrefix(part, "default:"):
-			i, err := strconv.Atoi64(part[8:])
+			i, err := strconv.ParseInt(part[8:], 10, 64)
 			if err == nil {
 				ret.defaultValue = new(int64)
 				*ret.defaultValue = i
diff --git a/src/pkg/encoding/base32/base32.go b/src/pkg/encoding/base32/base32.go
index 494c760d87d..c75c7c19d15 100644
--- a/src/pkg/encoding/base32/base32.go
+++ b/src/pkg/encoding/base32/base32.go
@@ -216,7 +216,7 @@ func (enc *Encoding) EncodedLen(n int) int { return (n + 4) / 5 * 8 }
 type CorruptInputError int64
 
 func (e CorruptInputError) Error() string {
-	return "illegal base32 data at input byte " + strconv.Itoa64(int64(e))
+	return "illegal base32 data at input byte " + strconv.FormatInt(int64(e), 10)
 }
 
 // decode is like Decode but returns an additional 'end' value, which
diff --git a/src/pkg/encoding/base64/base64.go b/src/pkg/encoding/base64/base64.go
index 945128947ab..889b565e3f5 100644
--- a/src/pkg/encoding/base64/base64.go
+++ b/src/pkg/encoding/base64/base64.go
@@ -203,7 +203,7 @@ func (enc *Encoding) EncodedLen(n int) int { return (n + 2) / 3 * 4 }
 type CorruptInputError int64
 
 func (e CorruptInputError) Error() string {
-	return "illegal base64 data at input byte " + strconv.Itoa64(int64(e))
+	return "illegal base64 data at input byte " + strconv.FormatInt(int64(e), 10)
 }
 
 // decode is like Decode but returns an additional 'end' value, which
diff --git a/src/pkg/encoding/git85/git.go b/src/pkg/encoding/git85/git.go
index b6ad6e2dd38..d383213ce87 100644
--- a/src/pkg/encoding/git85/git.go
+++ b/src/pkg/encoding/git85/git.go
@@ -15,7 +15,7 @@ import (
 type CorruptInputError int64
 
 func (e CorruptInputError) Error() string {
-	return "illegal git85 data at input byte " + strconv.Itoa64(int64(e))
+	return "illegal git85 data at input byte " + strconv.FormatInt(int64(e), 10)
 }
 
 const encode = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
diff --git a/src/pkg/encoding/json/decode.go b/src/pkg/encoding/json/decode.go
index 2ea06c50c27..0a700926296 100644
--- a/src/pkg/encoding/json/decode.go
+++ b/src/pkg/encoding/json/decode.go
@@ -642,7 +642,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value) {
 		default:
 			d.error(&UnmarshalTypeError{"number", v.Type()})
 		case reflect.Interface:
-			n, err := strconv.Atof64(s)
+			n, err := strconv.ParseFloat(s, 64)
 			if err != nil {
 				d.saveError(&UnmarshalTypeError{"number " + s, v.Type()})
 				break
@@ -650,7 +650,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value) {
 			v.Set(reflect.ValueOf(n))
 
 		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-			n, err := strconv.Atoi64(s)
+			n, err := strconv.ParseInt(s, 10, 64)
 			if err != nil || v.OverflowInt(n) {
 				d.saveError(&UnmarshalTypeError{"number " + s, v.Type()})
 				break
@@ -658,7 +658,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value) {
 			v.SetInt(n)
 
 		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-			n, err := strconv.Atoui64(s)
+			n, err := strconv.ParseUint(s, 10, 64)
 			if err != nil || v.OverflowUint(n) {
 				d.saveError(&UnmarshalTypeError{"number " + s, v.Type()})
 				break
@@ -666,7 +666,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value) {
 			v.SetUint(n)
 
 		case reflect.Float32, reflect.Float64:
-			n, err := strconv.AtofN(s, v.Type().Bits())
+			n, err := strconv.ParseFloat(s, v.Type().Bits())
 			if err != nil || v.OverflowFloat(n) {
 				d.saveError(&UnmarshalTypeError{"number " + s, v.Type()})
 				break
@@ -798,7 +798,7 @@ func (d *decodeState) literalInterface() interface{} {
 		if c != '-' && (c < '0' || c > '9') {
 			d.error(errPhase)
 		}
-		n, err := strconv.Atof64(string(item))
+		n, err := strconv.ParseFloat(string(item), 64)
 		if err != nil {
 			d.saveError(&UnmarshalTypeError{"number " + string(item), reflect.TypeOf(0.0)})
 		}
@@ -813,7 +813,7 @@ func getu4(s []byte) rune {
 	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
 		return -1
 	}
-	r, err := strconv.Btoui64(string(s[2:6]), 16)
+	r, err := strconv.ParseUint(string(s[2:6]), 16, 64)
 	if err != nil {
 		return -1
 	}
diff --git a/src/pkg/encoding/json/encode.go b/src/pkg/encoding/json/encode.go
index 14284f50e47..69deaf2a40d 100644
--- a/src/pkg/encoding/json/encode.go
+++ b/src/pkg/encoding/json/encode.go
@@ -275,13 +275,13 @@ func (e *encodeState) reflectValueQuoted(v reflect.Value, quoted bool) {
 		}
 
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		writeString(e, strconv.Itoa64(v.Int()))
+		writeString(e, strconv.FormatInt(v.Int(), 10))
 
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		writeString(e, strconv.Uitoa64(v.Uint()))
+		writeString(e, strconv.FormatUint(v.Uint(), 10))
 
 	case reflect.Float32, reflect.Float64:
-		writeString(e, strconv.FtoaN(v.Float(), 'g', -1, v.Type().Bits()))
+		writeString(e, strconv.FormatFloat(v.Float(), 'g', -1, v.Type().Bits()))
 
 	case reflect.String:
 		if quoted {
diff --git a/src/pkg/encoding/xml/marshal.go b/src/pkg/encoding/xml/marshal.go
index 691b70d2510..e94fdbc531f 100644
--- a/src/pkg/encoding/xml/marshal.go
+++ b/src/pkg/encoding/xml/marshal.go
@@ -173,15 +173,15 @@ func (p *printer) marshalValue(val reflect.Value, name string) error {
 
 	switch k := val.Kind(); k {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		p.WriteString(strconv.Itoa64(val.Int()))
+		p.WriteString(strconv.FormatInt(val.Int(), 10))
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		p.WriteString(strconv.Uitoa64(val.Uint()))
+		p.WriteString(strconv.FormatUint(val.Uint(), 10))
 	case reflect.Float32, reflect.Float64:
-		p.WriteString(strconv.Ftoa64(val.Float(), 'g', -1))
+		p.WriteString(strconv.FormatFloat(val.Float(), 'g', -1, 64))
 	case reflect.String:
 		Escape(p, []byte(val.String()))
 	case reflect.Bool:
-		p.WriteString(strconv.Btoa(val.Bool()))
+		p.WriteString(strconv.FormatBool(val.Bool()))
 	case reflect.Array:
 		// will be [...]byte
 		bytes := make([]byte, val.Len())
diff --git a/src/pkg/encoding/xml/read.go b/src/pkg/encoding/xml/read.go
index c6a3d75a801..6dd36541000 100644
--- a/src/pkg/encoding/xml/read.go
+++ b/src/pkg/encoding/xml/read.go
@@ -486,19 +486,19 @@ func copyValue(dst reflect.Value, src []byte) (err error) {
 	// Helper functions for integer and unsigned integer conversions
 	var itmp int64
 	getInt64 := func() bool {
-		itmp, err = strconv.Atoi64(string(src))
+		itmp, err = strconv.ParseInt(string(src), 10, 64)
 		// TODO: should check sizes
 		return err == nil
 	}
 	var utmp uint64
 	getUint64 := func() bool {
-		utmp, err = strconv.Atoui64(string(src))
+		utmp, err = strconv.ParseUint(string(src), 10, 64)
 		// TODO: check for overflow?
 		return err == nil
 	}
 	var ftmp float64
 	getFloat64 := func() bool {
-		ftmp, err = strconv.Atof64(string(src))
+		ftmp, err = strconv.ParseFloat(string(src), 64)
 		// TODO: check for overflow?
 		return err == nil
 	}
@@ -525,7 +525,7 @@ func copyValue(dst reflect.Value, src []byte) (err error) {
 		}
 		t.SetFloat(ftmp)
 	case reflect.Bool:
-		value, err := strconv.Atob(strings.TrimSpace(string(src)))
+		value, err := strconv.ParseBool(strings.TrimSpace(string(src)))
 		if err != nil {
 			return err
 		}
diff --git a/src/pkg/encoding/xml/xml.go b/src/pkg/encoding/xml/xml.go
index d67a299f5bb..d001c408923 100644
--- a/src/pkg/encoding/xml/xml.go
+++ b/src/pkg/encoding/xml/xml.go
@@ -889,9 +889,9 @@ Input:
 				var n uint64
 				var err error
 				if i >= 3 && s[1] == 'x' {
-					n, err = strconv.Btoui64(s[2:], 16)
+					n, err = strconv.ParseUint(s[2:], 16, 64)
 				} else {
-					n, err = strconv.Btoui64(s[1:], 10)
+					n, err = strconv.ParseUint(s[1:], 10, 64)
 				}
 				if err == nil && n <= unicode.MaxRune {
 					text = string(n)
diff --git a/src/pkg/exp/norm/maketables.go b/src/pkg/exp/norm/maketables.go
index 39bab7f0b6a..9a97831716b 100644
--- a/src/pkg/exp/norm/maketables.go
+++ b/src/pkg/exp/norm/maketables.go
@@ -226,7 +226,7 @@ func parseDecomposition(s string, skipfirst bool) (a []rune, e error) {
 		decomp = decomp[1:]
 	}
 	for _, d := range decomp {
-		point, err := strconv.Btoui64(d, 16)
+		point, err := strconv.ParseUint(d, 16, 64)
 		if err != nil {
 			return a, err
 		}
@@ -240,7 +240,7 @@ func parseCharacter(line string) {
 	if len(field) != NumField {
 		logger.Fatalf("%5s: %d fields (expected %d)\n", line, len(field), NumField)
 	}
-	x, err := strconv.Btoui64(field[FCodePoint], 16)
+	x, err := strconv.ParseUint(field[FCodePoint], 16, 64)
 	point := int(x)
 	if err != nil {
 		logger.Fatalf("%.5s...: %s", line, err)
@@ -264,7 +264,7 @@ func parseCharacter(line string) {
 	if state != SLast {
 		firstChar = lastChar
 	}
-	x, err = strconv.Atoui64(field[FCanonicalCombiningClass])
+	x, err = strconv.ParseUint(field[FCanonicalCombiningClass], 10, 64)
 	if err != nil {
 		logger.Fatalf("%U: bad ccc field: %s", int(x), err)
 	}
@@ -336,7 +336,7 @@ func parseExclusion(line string) int {
 	if len(matches) != 2 {
 		logger.Fatalf("%s: %d matches (expected 1)\n", line, len(matches))
 	}
-	point, err := strconv.Btoui64(matches[1], 16)
+	point, err := strconv.ParseUint(matches[1], 16, 64)
 	if err != nil {
 		logger.Fatalf("%.5s...: %s", line, err)
 	}
@@ -792,13 +792,13 @@ func testDerived() {
 			continue
 		}
 		rng := strings.Split(qc[1], "..")
-		i, err := strconv.Btoui64(rng[0], 16)
+		i, err := strconv.ParseUint(rng[0], 16, 64)
 		if err != nil {
 			log.Fatal(err)
 		}
 		j := i
 		if len(rng) > 1 {
-			j, err = strconv.Btoui64(rng[1], 16)
+			j, err = strconv.ParseUint(rng[1], 16, 64)
 			if err != nil {
 				log.Fatal(err)
 			}
diff --git a/src/pkg/exp/norm/normregtest.go b/src/pkg/exp/norm/normregtest.go
index 6610c257e51..d214ce11bc2 100644
--- a/src/pkg/exp/norm/normregtest.go
+++ b/src/pkg/exp/norm/normregtest.go
@@ -171,7 +171,7 @@ func loadTestData() {
 		counter++
 		for j := 1; j < len(m)-1; j++ {
 			for _, split := range strings.Split(m[j], " ") {
-				r, err := strconv.Btoui64(split, 16)
+				r, err := strconv.ParseUint(split, 16, 64)
 				if err != nil {
 					logger.Fatal(err)
 				}
diff --git a/src/pkg/exp/sql/convert.go b/src/pkg/exp/sql/convert.go
index 48e281203be..24315a0d351 100644
--- a/src/pkg/exp/sql/convert.go
+++ b/src/pkg/exp/sql/convert.go
@@ -95,7 +95,7 @@ func convertAssign(dest, src interface{}) error {
 	switch dv.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		s := asString(src)
-		i64, err := strconv.Atoi64(s)
+		i64, err := strconv.ParseInt(s, 10, 64)
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
@@ -106,7 +106,7 @@ func convertAssign(dest, src interface{}) error {
 		return nil
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		s := asString(src)
-		u64, err := strconv.Atoui64(s)
+		u64, err := strconv.ParseUint(s, 10, 64)
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
@@ -117,7 +117,7 @@ func convertAssign(dest, src interface{}) error {
 		return nil
 	case reflect.Float32, reflect.Float64:
 		s := asString(src)
-		f64, err := strconv.Atof64(s)
+		f64, err := strconv.ParseFloat(s, 64)
 		if err != nil {
 			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
 		}
diff --git a/src/pkg/exp/sql/driver/types.go b/src/pkg/exp/sql/driver/types.go
index 6e0ce4339cc..086b529c84f 100644
--- a/src/pkg/exp/sql/driver/types.go
+++ b/src/pkg/exp/sql/driver/types.go
@@ -54,13 +54,13 @@ func (boolType) ConvertValue(src interface{}) (interface{}, error) {
 	case bool:
 		return s, nil
 	case string:
-		b, err := strconv.Atob(s)
+		b, err := strconv.ParseBool(s)
 		if err != nil {
 			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
 		}
 		return b, nil
 	case []byte:
-		b, err := strconv.Atob(string(s))
+		b, err := strconv.ParseBool(string(s))
 		if err != nil {
 			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
 		}
diff --git a/src/pkg/exp/types/gcimporter.go b/src/pkg/exp/types/gcimporter.go
index b5fc357802a..6adcc2a9ad2 100644
--- a/src/pkg/exp/types/gcimporter.go
+++ b/src/pkg/exp/types/gcimporter.go
@@ -305,7 +305,7 @@ func (p *gcParser) parseArrayType() Type {
 	lit := p.expect(scanner.Int)
 	p.expect(']')
 	elt := p.parseType()
-	n, err := strconv.Atoui64(lit)
+	n, err := strconv.ParseUint(lit, 10, 64)
 	if err != nil {
 		p.error(err)
 	}
@@ -622,10 +622,11 @@ func (p *gcParser) parseNumber() Const {
 		// exponent (base 2)
 		p.next()
 		sign, val = p.parseInt()
-		exp, err := strconv.Atoui(val)
+		exp64, err := strconv.ParseUint(val, 10, 0)
 		if err != nil {
 			p.error(err)
 		}
+		exp := uint(exp64)
 		if sign == "-" {
 			denom := big.NewInt(1)
 			denom.Lsh(denom, exp)
diff --git a/src/pkg/expvar/expvar.go b/src/pkg/expvar/expvar.go
index 629280acf76..40f5441ddcb 100644
--- a/src/pkg/expvar/expvar.go
+++ b/src/pkg/expvar/expvar.go
@@ -44,7 +44,7 @@ type Int struct {
 	mu sync.Mutex
 }
 
-func (v *Int) String() string { return strconv.Itoa64(v.i) }
+func (v *Int) String() string { return strconv.FormatInt(v.i, 10) }
 
 func (v *Int) Add(delta int64) {
 	v.mu.Lock()
@@ -64,7 +64,7 @@ type Float struct {
 	mu sync.Mutex
 }
 
-func (v *Float) String() string { return strconv.Ftoa64(v.f, 'g', -1) }
+func (v *Float) String() string { return strconv.FormatFloat(v.f, 'g', -1, 64) }
 
 // Add adds delta to v.
 func (v *Float) Add(delta float64) {
diff --git a/src/pkg/flag/flag.go b/src/pkg/flag/flag.go
index 9f115d592bd..406ea77799d 100644
--- a/src/pkg/flag/flag.go
+++ b/src/pkg/flag/flag.go
@@ -79,7 +79,7 @@ func newBoolValue(val bool, p *bool) *boolValue {
 }
 
 func (b *boolValue) Set(s string) bool {
-	v, err := strconv.Atob(s)
+	v, err := strconv.ParseBool(s)
 	*b = boolValue(v)
 	return err == nil
 }
@@ -95,7 +95,7 @@ func newIntValue(val int, p *int) *intValue {
 }
 
 func (i *intValue) Set(s string) bool {
-	v, err := strconv.Btoi64(s, 0)
+	v, err := strconv.ParseInt(s, 0, 64)
 	*i = intValue(v)
 	return err == nil
 }
@@ -111,7 +111,7 @@ func newInt64Value(val int64, p *int64) *int64Value {
 }
 
 func (i *int64Value) Set(s string) bool {
-	v, err := strconv.Btoi64(s, 0)
+	v, err := strconv.ParseInt(s, 0, 64)
 	*i = int64Value(v)
 	return err == nil
 }
@@ -127,7 +127,7 @@ func newUintValue(val uint, p *uint) *uintValue {
 }
 
 func (i *uintValue) Set(s string) bool {
-	v, err := strconv.Btoui64(s, 0)
+	v, err := strconv.ParseUint(s, 0, 64)
 	*i = uintValue(v)
 	return err == nil
 }
@@ -143,7 +143,7 @@ func newUint64Value(val uint64, p *uint64) *uint64Value {
 }
 
 func (i *uint64Value) Set(s string) bool {
-	v, err := strconv.Btoui64(s, 0)
+	v, err := strconv.ParseUint(s, 0, 64)
 	*i = uint64Value(v)
 	return err == nil
 }
@@ -174,7 +174,7 @@ func newFloat64Value(val float64, p *float64) *float64Value {
 }
 
 func (f *float64Value) Set(s string) bool {
-	v, err := strconv.Atof64(s)
+	v, err := strconv.ParseFloat(s, 64)
 	*f = float64Value(v)
 	return err == nil
 }
diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index 3957a5a261d..fbafa9d9ad9 100644
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -360,44 +360,44 @@ func (f *fmt) plusSpace(s string) {
 }
 
 // fmt_e64 formats a float64 in the form -1.23e+12.
-func (f *fmt) fmt_e64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'e', doPrec(f, 6))) }
+func (f *fmt) fmt_e64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'e', doPrec(f, 6), 64)) }
 
 // fmt_E64 formats a float64 in the form -1.23E+12.
-func (f *fmt) fmt_E64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'E', doPrec(f, 6))) }
+func (f *fmt) fmt_E64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'E', doPrec(f, 6), 64)) }
 
 // fmt_f64 formats a float64 in the form -1.23.
-func (f *fmt) fmt_f64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'f', doPrec(f, 6))) }
+func (f *fmt) fmt_f64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'f', doPrec(f, 6), 64)) }
 
 // fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
-func (f *fmt) fmt_g64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'g', doPrec(f, -1))) }
+func (f *fmt) fmt_g64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'g', doPrec(f, -1), 64)) }
 
 // fmt_g64 formats a float64 in the 'f' or 'E' form according to size.
-func (f *fmt) fmt_G64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'G', doPrec(f, -1))) }
+func (f *fmt) fmt_G64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'G', doPrec(f, -1), 64)) }
 
 // fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
-func (f *fmt) fmt_fb64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'b', 0)) }
+func (f *fmt) fmt_fb64(v float64) { f.plusSpace(strconv.FormatFloat(v, 'b', 0, 64)) }
 
 // float32
 // cannot defer to float64 versions
 // because it will get rounding wrong in corner cases.
 
 // fmt_e32 formats a float32 in the form -1.23e+12.
-func (f *fmt) fmt_e32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'e', doPrec(f, 6))) }
+func (f *fmt) fmt_e32(v float32) { f.plusSpace(strconv.FormatFloat(float64(v), 'e', doPrec(f, 6), 32)) }
 
 // fmt_E32 formats a float32 in the form -1.23E+12.
-func (f *fmt) fmt_E32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'E', doPrec(f, 6))) }
+func (f *fmt) fmt_E32(v float32) { f.plusSpace(strconv.FormatFloat(float64(v), 'E', doPrec(f, 6), 32)) }
 
 // fmt_f32 formats a float32 in the form -1.23.
-func (f *fmt) fmt_f32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'f', doPrec(f, 6))) }
+func (f *fmt) fmt_f32(v float32) { f.plusSpace(strconv.FormatFloat(float64(v), 'f', doPrec(f, 6), 32)) }
 
 // fmt_g32 formats a float32 in the 'f' or 'e' form according to size.
-func (f *fmt) fmt_g32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'g', doPrec(f, -1))) }
+func (f *fmt) fmt_g32(v float32) { f.plusSpace(strconv.FormatFloat(float64(v), 'g', doPrec(f, -1), 32)) }
 
 // fmt_G32 formats a float32 in the 'f' or 'E' form according to size.
-func (f *fmt) fmt_G32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'G', doPrec(f, -1))) }
+func (f *fmt) fmt_G32(v float32) { f.plusSpace(strconv.FormatFloat(float64(v), 'G', doPrec(f, -1), 32)) }
 
 // fmt_fb32 formats a float32 in the form -123p3 (exponent is power of 2).
-func (f *fmt) fmt_fb32(v float32) { f.padString(strconv.Ftoa32(v, 'b', 0)) }
+func (f *fmt) fmt_fb32(v float32) { f.padString(strconv.FormatFloat(float64(v), 'b', 0, 32)) }
 
 // fmt_c64 formats a complex64 according to the verb.
 func (f *fmt) fmt_c64(v complex64, verb rune) {
diff --git a/src/pkg/fmt/scan.go b/src/pkg/fmt/scan.go
index 85571e80c7a..281525112e1 100644
--- a/src/pkg/fmt/scan.go
+++ b/src/pkg/fmt/scan.go
@@ -613,7 +613,7 @@ func (s *ss) scanInt(verb rune, bitSize int) int64 {
 		}
 	}
 	tok := s.scanNumber(digits, haveDigits)
-	i, err := strconv.Btoi64(tok, base)
+	i, err := strconv.ParseInt(tok, base, 64)
 	if err != nil {
 		s.error(err)
 	}
@@ -643,7 +643,7 @@ func (s *ss) scanUint(verb rune, bitSize int) uint64 {
 		base, digits, haveDigits = s.scanBasePrefix()
 	}
 	tok := s.scanNumber(digits, haveDigits)
-	i, err := strconv.Btoui64(tok, base)
+	i, err := strconv.ParseUint(tok, base, 64)
 	if err != nil {
 		s.error(err)
 	}
@@ -719,7 +719,7 @@ func (s *ss) convertFloat(str string, n int) float64 {
 	if p := strings.Index(str, "p"); p >= 0 {
 		// Atof doesn't handle power-of-2 exponents,
 		// but they're easy to evaluate.
-		f, err := strconv.AtofN(str[:p], n)
+		f, err := strconv.ParseFloat(str[:p], n)
 		if err != nil {
 			// Put full string into error.
 			if e, ok := err.(*strconv.NumError); ok {
@@ -737,7 +737,7 @@ func (s *ss) convertFloat(str string, n int) float64 {
 		}
 		return math.Ldexp(f, n)
 	}
-	f, err := strconv.AtofN(str, n)
+	f, err := strconv.ParseFloat(str, n)
 	if err != nil {
 		s.error(err)
 	}
diff --git a/src/pkg/html/template/css_test.go b/src/pkg/html/template/css_test.go
index 0d94bdcf18c..a735638b031 100644
--- a/src/pkg/html/template/css_test.go
+++ b/src/pkg/html/template/css_test.go
@@ -113,7 +113,7 @@ func TestDecodeCSS(t *testing.T) {
 
 func TestHexDecode(t *testing.T) {
 	for i := 0; i < 0x200000; i += 101 /* coprime with 16 */ {
-		s := strconv.Itob(i, 16)
+		s := strconv.FormatInt(int64(i), 16)
 		if got := int(hexDecode([]byte(s))); got != i {
 			t.Errorf("%s: want %d but got %d", s, i, got)
 		}
diff --git a/src/pkg/image/png/writer.go b/src/pkg/image/png/writer.go
index 48089ff75c7..641eae1bb8e 100644
--- a/src/pkg/image/png/writer.go
+++ b/src/pkg/image/png/writer.go
@@ -429,7 +429,7 @@ func Encode(w io.Writer, m image.Image) error {
 	// also rejected.
 	mw, mh := int64(m.Bounds().Dx()), int64(m.Bounds().Dy())
 	if mw <= 0 || mh <= 0 || mw >= 1<<32 || mh >= 1<<32 {
-		return FormatError("invalid image size: " + strconv.Itoa64(mw) + "x" + strconv.Itoa64(mw))
+		return FormatError("invalid image size: " + strconv.FormatInt(mw, 10) + "x" + strconv.FormatInt(mw, 10))
 	}
 
 	var e encoder
diff --git a/src/pkg/net/http/cgi/child.go b/src/pkg/net/http/cgi/child.go
index e188cd4a250..e6c3ef911ab 100644
--- a/src/pkg/net/http/cgi/child.go
+++ b/src/pkg/net/http/cgi/child.go
@@ -70,7 +70,7 @@ func RequestFromMap(params map[string]string) (*http.Request, error) {
 	r.Host = params["HTTP_HOST"]
 
 	if lenstr := params["CONTENT_LENGTH"]; lenstr != "" {
-		clen, err := strconv.Atoi64(lenstr)
+		clen, err := strconv.ParseInt(lenstr, 10, 64)
 		if err != nil {
 			return nil, errors.New("cgi: bad CONTENT_LENGTH in environment: " + lenstr)
 		}
diff --git a/src/pkg/net/http/chunked.go b/src/pkg/net/http/chunked.go
index 74c41aabd41..60a478fd8fa 100644
--- a/src/pkg/net/http/chunked.go
+++ b/src/pkg/net/http/chunked.go
@@ -48,7 +48,7 @@ func (cr *chunkedReader) beginChunk() {
 	if cr.err != nil {
 		return
 	}
-	cr.n, cr.err = strconv.Btoui64(line, 16)
+	cr.n, cr.err = strconv.ParseUint(line, 16, 64)
 	if cr.err != nil {
 		return
 	}
@@ -147,7 +147,7 @@ func (cw *chunkedWriter) Write(data []byte) (n int, err error) {
 		return 0, nil
 	}
 
-	head := strconv.Itob(len(data), 16) + "\r\n"
+	head := strconv.FormatInt(int64(len(data)), 16) + "\r\n"
 
 	if _, err = io.WriteString(cw.Wire, head); err != nil {
 		return 0, err
diff --git a/src/pkg/net/http/fs.go b/src/pkg/net/http/fs.go
index 70e7849f167..1392ca68ad6 100644
--- a/src/pkg/net/http/fs.go
+++ b/src/pkg/net/http/fs.go
@@ -220,7 +220,7 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 
 	w.Header().Set("Accept-Ranges", "bytes")
 	if w.Header().Get("Content-Encoding") == "" {
-		w.Header().Set("Content-Length", strconv.Itoa64(size))
+		w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
 	}
 
 	w.WriteHeader(code)
@@ -295,7 +295,7 @@ func parseRange(s string, size int64) ([]httpRange, error) {
 		if start == "" {
 			// If no start is specified, end specifies the
 			// range start relative to the end of the file.
-			i, err := strconv.Atoi64(end)
+			i, err := strconv.ParseInt(end, 10, 64)
 			if err != nil {
 				return nil, errors.New("invalid range")
 			}
@@ -305,7 +305,7 @@ func parseRange(s string, size int64) ([]httpRange, error) {
 			r.start = size - i
 			r.length = size - r.start
 		} else {
-			i, err := strconv.Atoi64(start)
+			i, err := strconv.ParseInt(start, 10, 64)
 			if err != nil || i > size || i < 0 {
 				return nil, errors.New("invalid range")
 			}
@@ -314,7 +314,7 @@ func parseRange(s string, size int64) ([]httpRange, error) {
 				// If no end is specified, range extends to end of the file.
 				r.length = size - r.start
 			} else {
-				i, err := strconv.Atoi64(end)
+				i, err := strconv.ParseInt(end, 10, 64)
 				if err != nil || r.start > i {
 					return nil, errors.New("invalid range")
 				}
diff --git a/src/pkg/net/http/httputil/chunked.go b/src/pkg/net/http/httputil/chunked.go
index 69bcc0e816f..29eaf3475f1 100644
--- a/src/pkg/net/http/httputil/chunked.go
+++ b/src/pkg/net/http/httputil/chunked.go
@@ -50,7 +50,7 @@ func (cr *chunkedReader) beginChunk() {
 	if cr.err != nil {
 		return
 	}
-	cr.n, cr.err = strconv.Btoui64(line, 16)
+	cr.n, cr.err = strconv.ParseUint(line, 16, 64)
 	if cr.err != nil {
 		return
 	}
@@ -149,7 +149,7 @@ func (cw *chunkedWriter) Write(data []byte) (n int, err error) {
 		return 0, nil
 	}
 
-	head := strconv.Itob(len(data), 16) + "\r\n"
+	head := strconv.FormatInt(int64(len(data)), 16) + "\r\n"
 
 	if _, err = io.WriteString(cw.Wire, head); err != nil {
 		return 0, err
diff --git a/src/pkg/net/http/pprof/pprof.go b/src/pkg/net/http/pprof/pprof.go
index 2de147579d1..21eac4743ac 100644
--- a/src/pkg/net/http/pprof/pprof.go
+++ b/src/pkg/net/http/pprof/pprof.go
@@ -63,7 +63,7 @@ func Heap(w http.ResponseWriter, r *http.Request) {
 // Profile responds with the pprof-formatted cpu profile.
 // The package initialization registers it as /debug/pprof/profile.
 func Profile(w http.ResponseWriter, r *http.Request) {
-	sec, _ := strconv.Atoi64(r.FormValue("seconds"))
+	sec, _ := strconv.ParseInt(r.FormValue("seconds"), 10, 64)
 	if sec == 0 {
 		sec = 30
 	}
@@ -111,7 +111,7 @@ func Symbol(w http.ResponseWriter, r *http.Request) {
 		if err == nil {
 			word = word[0 : len(word)-1] // trim +
 		}
-		pc, _ := strconv.Btoui64(string(word), 0)
+		pc, _ := strconv.ParseUint(string(word), 0, 64)
 		if pc != 0 {
 			f := runtime.FuncForPC(uintptr(pc))
 			if f != nil {
diff --git a/src/pkg/net/http/server.go b/src/pkg/net/http/server.go
index 125f3f214bb..c100e4d5c6d 100644
--- a/src/pkg/net/http/server.go
+++ b/src/pkg/net/http/server.go
@@ -288,7 +288,7 @@ func (w *response) WriteHeader(code int) {
 	var contentLength int64
 	if clenStr := w.header.Get("Content-Length"); clenStr != "" {
 		var err error
-		contentLength, err = strconv.Atoi64(clenStr)
+		contentLength, err = strconv.ParseInt(clenStr, 10, 64)
 		if err == nil {
 			hasCL = true
 		} else {
diff --git a/src/pkg/net/http/transfer.go b/src/pkg/net/http/transfer.go
index d25c8fcde42..ef9564af9c5 100644
--- a/src/pkg/net/http/transfer.go
+++ b/src/pkg/net/http/transfer.go
@@ -147,7 +147,7 @@ func (t *transferWriter) WriteHeader(w io.Writer) (err error) {
 	// TransferEncoding)
 	if t.shouldSendContentLength() {
 		io.WriteString(w, "Content-Length: ")
-		_, err = io.WriteString(w, strconv.Itoa64(t.ContentLength)+"\r\n")
+		_, err = io.WriteString(w, strconv.FormatInt(t.ContentLength, 10)+"\r\n")
 		if err != nil {
 			return
 		}
@@ -432,7 +432,7 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
 	// Logic based on Content-Length
 	cl := strings.TrimSpace(header.Get("Content-Length"))
 	if cl != "" {
-		n, err := strconv.Atoi64(cl)
+		n, err := strconv.ParseInt(cl, 10, 64)
 		if err != nil || n < 0 {
 			return -1, &badStringError{"bad Content-Length", cl}
 		}
diff --git a/src/pkg/net/mail/message.go b/src/pkg/net/mail/message.go
index e1afa32062f..bf22c711e49 100644
--- a/src/pkg/net/mail/message.go
+++ b/src/pkg/net/mail/message.go
@@ -481,7 +481,7 @@ func (qd qDecoder) Read(p []byte) (n int, err error) {
 		if _, err := io.ReadFull(qd.r, qd.scratch[:2]); err != nil {
 			return 0, err
 		}
-		x, err := strconv.Btoi64(string(qd.scratch[:2]), 16)
+		x, err := strconv.ParseInt(string(qd.scratch[:2]), 16, 64)
 		if err != nil {
 			return 0, fmt.Errorf("mail: invalid RFC 2047 encoding: %q", qd.scratch[:2])
 		}
diff --git a/src/pkg/old/template/parse.go b/src/pkg/old/template/parse.go
index b8c806472ee..e1bfa472499 100644
--- a/src/pkg/old/template/parse.go
+++ b/src/pkg/old/template/parse.go
@@ -424,11 +424,11 @@ func (t *Template) newVariable(words []string) *variableElement {
 			}
 
 		case '.', '+', '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
-			v, err := strconv.Btoi64(word, 0)
+			v, err := strconv.ParseInt(word, 0, 64)
 			if err == nil {
 				args[i] = v
 			} else {
-				v, err := strconv.Atof64(word)
+				v, err := strconv.ParseFloat(word, 64)
 				args[i], lerr = v, err
 			}
 
diff --git a/src/pkg/reflect/tostring_test.go b/src/pkg/reflect/tostring_test.go
index 5f5c52b778a..7486a9bfca3 100644
--- a/src/pkg/reflect/tostring_test.go
+++ b/src/pkg/reflect/tostring_test.go
@@ -23,14 +23,14 @@ func valueToString(val Value) string {
 	typ := val.Type()
 	switch val.Kind() {
 	case Int, Int8, Int16, Int32, Int64:
-		return strconv.Itoa64(val.Int())
+		return strconv.FormatInt(val.Int(), 10)
 	case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
-		return strconv.Uitoa64(val.Uint())
+		return strconv.FormatUint(val.Uint(), 10)
 	case Float32, Float64:
-		return strconv.Ftoa64(val.Float(), 'g', -1)
+		return strconv.FormatFloat(val.Float(), 'g', -1, 64)
 	case Complex64, Complex128:
 		c := val.Complex()
-		return strconv.Ftoa64(real(c), 'g', -1) + "+" + strconv.Ftoa64(imag(c), 'g', -1) + "i"
+		return strconv.FormatFloat(real(c), 'g', -1, 64) + "+" + strconv.FormatFloat(imag(c), 'g', -1, 64) + "i"
 	case String:
 		return val.String()
 	case Bool:
@@ -88,7 +88,7 @@ func valueToString(val Value) string {
 		return typ.String() + "(" + valueToString(val.Elem()) + ")"
 	case Func:
 		v := val
-		return typ.String() + "(" + strconv.Uitoa64(uint64(v.Pointer())) + ")"
+		return typ.String() + "(" + strconv.FormatUint(uint64(v.Pointer()), 10) + ")"
 	default:
 		panic("valueToString: can't print type " + typ.String())
 	}
diff --git a/src/pkg/regexp/syntax/prog.go b/src/pkg/regexp/syntax/prog.go
index f5b697a59ae..84ebb835581 100644
--- a/src/pkg/regexp/syntax/prog.go
+++ b/src/pkg/regexp/syntax/prog.go
@@ -267,7 +267,7 @@ func dumpProg(b *bytes.Buffer, p *Prog) {
 }
 
 func u32(i uint32) string {
-	return strconv.Uitoa64(uint64(i))
+	return strconv.FormatUint(uint64(i), 10)
 }
 
 func dumpInst(b *bytes.Buffer, i *Inst) {
diff --git a/src/pkg/regexp/syntax/regexp.go b/src/pkg/regexp/syntax/regexp.go
index b5ddab1d16b..adcfe294495 100644
--- a/src/pkg/regexp/syntax/regexp.go
+++ b/src/pkg/regexp/syntax/regexp.go
@@ -277,7 +277,7 @@ func escape(b *bytes.Buffer, r rune, force bool) {
 	default:
 		if r < 0x100 {
 			b.WriteString(`\x`)
-			s := strconv.Itob(int(r), 16)
+			s := strconv.FormatInt(int64(r), 16)
 			if len(s) == 1 {
 				b.WriteRune('0')
 			}
@@ -285,7 +285,7 @@ func escape(b *bytes.Buffer, r rune, force bool) {
 			break
 		}
 		b.WriteString(`\x{`)
-		b.WriteString(strconv.Itob(int(r), 16))
+		b.WriteString(strconv.FormatInt(int64(r), 16))
 		b.WriteString(`}`)
 	}
 }
diff --git a/src/pkg/text/template/parse/node.go b/src/pkg/text/template/parse/node.go
index a4e5514768a..4f43424239a 100644
--- a/src/pkg/text/template/parse/node.go
+++ b/src/pkg/text/template/parse/node.go
@@ -267,7 +267,7 @@ func newNumber(text string, typ itemType) (*NumberNode, error) {
 	}
 	// Imaginary constants can only be complex unless they are zero.
 	if len(text) > 0 && text[len(text)-1] == 'i' {
-		f, err := strconv.Atof64(text[:len(text)-1])
+		f, err := strconv.ParseFloat(text[:len(text)-1], 64)
 		if err == nil {
 			n.IsComplex = true
 			n.Complex128 = complex(0, f)
@@ -276,12 +276,12 @@ func newNumber(text string, typ itemType) (*NumberNode, error) {
 		}
 	}
 	// Do integer test first so we get 0x123 etc.
-	u, err := strconv.Btoui64(text, 0) // will fail for -0; fixed below.
+	u, err := strconv.ParseUint(text, 0, 64) // will fail for -0; fixed below.
 	if err == nil {
 		n.IsUint = true
 		n.Uint64 = u
 	}
-	i, err := strconv.Btoi64(text, 0)
+	i, err := strconv.ParseInt(text, 0, 64)
 	if err == nil {
 		n.IsInt = true
 		n.Int64 = i
@@ -298,7 +298,7 @@ func newNumber(text string, typ itemType) (*NumberNode, error) {
 		n.IsFloat = true
 		n.Float64 = float64(n.Uint64)
 	} else {
-		f, err := strconv.Atof64(text)
+		f, err := strconv.ParseFloat(text, 64)
 		if err == nil {
 			n.IsFloat = true
 			n.Float64 = f
diff --git a/src/pkg/time/time_test.go b/src/pkg/time/time_test.go
index 9590e281a66..6d1e79b542b 100644
--- a/src/pkg/time/time_test.go
+++ b/src/pkg/time/time_test.go
@@ -339,7 +339,7 @@ func checkTime(time Time, test *ParseTest, t *testing.T) {
 		t.Errorf("%s: bad second: %d not %d", test.name, time.Second(), 57)
 	}
 	// Nanoseconds must be checked against the precision of the input.
-	nanosec, err := strconv.Atoui("012345678"[:test.fracDigits] + "000000000"[:9-test.fracDigits])
+	nanosec, err := strconv.ParseUint("012345678"[:test.fracDigits]+"000000000"[:9-test.fracDigits], 10, 0)
 	if err != nil {
 		panic(err)
 	}
diff --git a/src/pkg/unicode/maketables.go b/src/pkg/unicode/maketables.go
index a405da30766..393f8eadea0 100644
--- a/src/pkg/unicode/maketables.go
+++ b/src/pkg/unicode/maketables.go
@@ -199,7 +199,7 @@ func parseCategory(line string) (state State) {
 	if len(field) != NumField {
 		logger.Fatalf("%5s: %d fields (expected %d)\n", line, len(field), NumField)
 	}
-	point, err := strconv.Btoui64(field[FCodePoint], 16)
+	point, err := strconv.ParseUint(field[FCodePoint], 16, 64)
 	if err != nil {
 		logger.Fatalf("%.5s...: %s", line, err)
 	}
@@ -261,7 +261,7 @@ func (char *Char) letterValue(s string, cas string) rune {
 	if s == "" {
 		return 0
 	}
-	v, err := strconv.Btoui64(s, 16)
+	v, err := strconv.ParseUint(s, 16, 64)
 	if err != nil {
 		char.dump(cas)
 		logger.Fatalf("%U: bad letter(%s): %s", char.codePoint, s, err)
@@ -377,11 +377,11 @@ func loadCasefold() {
 			// Only care about 'common' and 'simple' foldings.
 			continue
 		}
-		p1, err := strconv.Btoui64(field[0], 16)
+		p1, err := strconv.ParseUint(field[0], 16, 64)
 		if err != nil {
 			logger.Fatalf("CaseFolding.txt %.5s...: %s", line, err)
 		}
-		p2, err := strconv.Btoui64(field[2], 16)
+		p2, err := strconv.ParseUint(field[2], 16, 64)
 		if err != nil {
 			logger.Fatalf("CaseFolding.txt %.5s...: %s", line, err)
 		}
@@ -628,13 +628,13 @@ func parseScript(line string, scripts map[string][]Script) {
 	if len(matches) != 4 {
 		logger.Fatalf("%s: %d matches (expected 3)\n", line, len(matches))
 	}
-	lo, err := strconv.Btoui64(matches[1], 16)
+	lo, err := strconv.ParseUint(matches[1], 16, 64)
 	if err != nil {
 		logger.Fatalf("%.5s...: %s", line, err)
 	}
 	hi := lo
 	if len(matches[2]) > 2 { // ignore leading ..
-		hi, err = strconv.Btoui64(matches[2][2:], 16)
+		hi, err = strconv.ParseUint(matches[2][2:], 16, 64)
 		if err != nil {
 			logger.Fatalf("%.5s...: %s", line, err)
 		}
diff --git a/src/pkg/websocket/hixie.go b/src/pkg/websocket/hixie.go
index ec7b7ae0a45..d0ddbeeb484 100644
--- a/src/pkg/websocket/hixie.go
+++ b/src/pkg/websocket/hixie.go
@@ -365,13 +365,13 @@ func hixie76ClientHandshake(config *Config, br *bufio.Reader, bw *bufio.Writer)
 	key2, number2 := generateKeyNumber()
 	if config.handshakeData != nil {
 		key1 = config.handshakeData["key1"]
-		n, err := strconv.Atoui(config.handshakeData["number1"])
+		n, err := strconv.ParseUint(config.handshakeData["number1"], 10, 32)
 		if err != nil {
 			panic(err)
 		}
 		number1 = uint32(n)
 		key2 = config.handshakeData["key2"]
-		n, err = strconv.Atoui(config.handshakeData["number2"])
+		n, err = strconv.ParseUint(config.handshakeData["number2"], 10, 32)
 		if err != nil {
 			panic(err)
 		}
diff --git a/test/fixedbugs/bug120.go b/test/fixedbugs/bug120.go
index 2a71957d84b..bf401bf3048 100644
--- a/test/fixedbugs/bug120.go
+++ b/test/fixedbugs/bug120.go
@@ -41,16 +41,16 @@ func main() {
 	ok := true
 	for i := 0; i < len(tests); i++ {
 		t := tests[i]
-		v := strconv.Ftoa64(t.f, 'g', -1)
+		v := strconv.FormatFloat(t.f, 'g', -1, 64)
 		if v != t.out {
 			println("Bad float64 const:", t.in, "want", t.out, "got", v)
-			x, err := strconv.Atof64(t.out)
+			x, err := strconv.ParseFloat(t.out, 64)
 			if err != nil {
 				println("bug120: strconv.Atof64", t.out)
 				panic("fail")
 			}
-			println("\twant exact:", strconv.Ftoa64(x, 'g', 1000))
-			println("\tgot exact: ", strconv.Ftoa64(t.f, 'g', 1000))
+			println("\twant exact:", strconv.FormatFloat(x, 'g', 1000, 64))
+			println("\tgot exact: ", strconv.FormatFloat(t.f, 'g', 1000, 64))
 			ok = false
 		}
 	}
diff --git a/test/fixedbugs/bug260.go b/test/fixedbugs/bug260.go
index 34757c70eef..91dc89f77a5 100644
--- a/test/fixedbugs/bug260.go
+++ b/test/fixedbugs/bug260.go
@@ -24,8 +24,8 @@ func main() {
 	report := len(os.Args) > 1
 	status := 0
 	var b1 [10]T1
-	a0, _ := strconv.Btoui64(fmt.Sprintf("%p", &b1[0])[2:], 16)
-	a1, _ := strconv.Btoui64(fmt.Sprintf("%p", &b1[1])[2:], 16)
+	a0, _ := strconv.ParseUint(fmt.Sprintf("%p", &b1[0])[2:], 16, 64)
+	a1, _ := strconv.ParseUint(fmt.Sprintf("%p", &b1[1])[2:], 16, 64)
 	if a1 != a0+1 {
 		fmt.Println("FAIL")
 		if report {
@@ -34,8 +34,8 @@ func main() {
 		status = 1
 	}
 	var b2 [10]T2
-	a0, _ = strconv.Btoui64(fmt.Sprintf("%p", &b2[0])[2:], 16)
-	a1, _ = strconv.Btoui64(fmt.Sprintf("%p", &b2[1])[2:], 16)
+	a0, _ = strconv.ParseUint(fmt.Sprintf("%p", &b2[0])[2:], 16, 64)
+	a1, _ = strconv.ParseUint(fmt.Sprintf("%p", &b2[1])[2:], 16, 64)
 	if a1 != a0+2 {
 		if status == 0 {
 			fmt.Println("FAIL")
@@ -46,8 +46,8 @@ func main() {
 		}
 	}
 	var b4 [10]T4
-	a0, _ = strconv.Btoui64(fmt.Sprintf("%p", &b4[0])[2:], 16)
-	a1, _ = strconv.Btoui64(fmt.Sprintf("%p", &b4[1])[2:], 16)
+	a0, _ = strconv.ParseUint(fmt.Sprintf("%p", &b4[0])[2:], 16, 64)
+	a1, _ = strconv.ParseUint(fmt.Sprintf("%p", &b4[1])[2:], 16, 64)
 	if a1 != a0+4 {
 		if status == 0 {
 			fmt.Println("FAIL")