diff --git a/src/cmd/link/dead_test.go b/src/cmd/link/dead_test.go
index 0e00c7da4b..2e179b453b 100644
--- a/src/cmd/link/dead_test.go
+++ b/src/cmd/link/dead_test.go
@@ -92,6 +92,6 @@ func checkDeadSlice(t *testing.T, obj, name string, old, new []*Sym) {
 		new = new[1:]
 	}
 	if len(new) > 0 {
-		t.Errorf("%s: %s has unexpected symbols: %v", new)
+		t.Errorf("%s: %s has unexpected symbols: %v", obj, name, new)
 	}
 }
diff --git a/src/cmd/link/macho_test.go b/src/cmd/link/macho_test.go
index 62b1327497..37c4418b77 100644
--- a/src/cmd/link/macho_test.go
+++ b/src/cmd/link/macho_test.go
@@ -324,7 +324,7 @@ func machoRead(arch machoArch, data []byte) (*Prog, error) {
 			}
 			if load.Maxprot != maxprot || load.Prot != prot {
 				errorf("segment %q protection is %d, %d, want %d, %d",
-					load.Maxprot, load.Prot, maxprot, prot)
+					load.Name, load.Maxprot, load.Prot, maxprot, prot)
 			}
 
 			for len(msects) > 0 && msects[0].Addr < load.Addr+load.Memsz {
@@ -374,7 +374,7 @@ func machoRead(arch machoArch, data []byte) (*Prog, error) {
 					flags = 1
 				}
 				if msect.Flags != flags {
-					errorf("section %q flags = %#x, want %#x", msect.Flags, flags)
+					errorf("section %q flags = %#x, want %#x", msect.Name, msect.Flags, flags)
 				}
 				sect := &Section{
 					Name:     strings.ToLower(strings.TrimPrefix(msect.Name, "__")),
diff --git a/src/cmd/link/prog_test.go b/src/cmd/link/prog_test.go
index 768b11fc47..0853506957 100644
--- a/src/cmd/link/prog_test.go
+++ b/src/cmd/link/prog_test.go
@@ -75,11 +75,11 @@ func diffProg(p, q *Prog) []string {
 
 		for j := 0; j < len(pseg.Sections) || j < len(qseg.Sections); j++ {
 			if j >= len(pseg.Sections) {
-				errors = append(errors, fmt.Sprintf("segment %q missing section %q", qseg.Sections[i].Name))
+				errors = append(errors, fmt.Sprintf("segment %q missing section %q", pseg.Name, qseg.Sections[i].Name))
 				continue
 			}
 			if j >= len(qseg.Sections) {
-				errors = append(errors, fmt.Sprintf("segment %q has extra section %q", pseg.Sections[i].Name))
+				errors = append(errors, fmt.Sprintf("segment %q has extra section %q", pseg.Name, pseg.Sections[i].Name))
 				continue
 			}
 			psect := pseg.Sections[j]
diff --git a/src/cmd/pack/pack_test.go b/src/cmd/pack/pack_test.go
index b2be74b097..8ecca98e63 100644
--- a/src/cmd/pack/pack_test.go
+++ b/src/cmd/pack/pack_test.go
@@ -210,7 +210,7 @@ func TestHello(t *testing.T) {
 	run("go", "tool", char+"l", "-o", "a.out", "hello.a")
 	out := run("./a.out")
 	if out != "hello world\n" {
-		t.Fatal("incorrect output: %q, want %q", out, "hello world\n")
+		t.Fatalf("incorrect output: %q, want %q", out, "hello world\n")
 	}
 }
 
@@ -271,7 +271,7 @@ func TestLargeDefs(t *testing.T) {
 	run("go", "tool", char+"l", "-L", ".", "-o", "a.out", "main."+char)
 	out := run("./a.out")
 	if out != "ok\n" {
-		t.Fatal("incorrect output: %q, want %q", out, "ok\n")
+		t.Fatalf("incorrect output: %q, want %q", out, "ok\n")
 	}
 }
 
diff --git a/src/pkg/archive/tar/reader_test.go b/src/pkg/archive/tar/reader_test.go
index 55b19d3c2e..6d4e06a58d 100644
--- a/src/pkg/archive/tar/reader_test.go
+++ b/src/pkg/archive/tar/reader_test.go
@@ -618,7 +618,7 @@ func TestSparseFileReader(t *testing.T) {
 			tot: test.realSize,
 		}
 		if sfr.numBytes() != nb {
-			t.Errorf("test %d: Before reading, sfr.numBytes() = %d, want %d", i, sfr.numBytes, nb)
+			t.Errorf("test %d: Before reading, sfr.numBytes() = %d, want %d", i, sfr.numBytes(), nb)
 		}
 		buf, err := ioutil.ReadAll(sfr)
 		if err != nil {
diff --git a/src/pkg/crypto/x509/x509_test.go b/src/pkg/crypto/x509/x509_test.go
index 4b4b9d7c76..ce9062c4b4 100644
--- a/src/pkg/crypto/x509/x509_test.go
+++ b/src/pkg/crypto/x509/x509_test.go
@@ -395,7 +395,7 @@ func TestCreateSelfSignedCertificate(t *testing.T) {
 		}
 
 		if cert.SignatureAlgorithm != test.sigAlgo {
-			t.Errorf("%s: SignatureAlgorithm wasn't copied from template. Got %s, want %s", test.name, cert.SignatureAlgorithm, test.sigAlgo)
+			t.Errorf("%s: SignatureAlgorithm wasn't copied from template. Got %v, want %v", test.name, cert.SignatureAlgorithm, test.sigAlgo)
 		}
 
 		if !reflect.DeepEqual(cert.ExtKeyUsage, testExtKeyUsage) {
diff --git a/src/pkg/debug/macho/file_test.go b/src/pkg/debug/macho/file_test.go
index 0de9184c22..4797780ce7 100644
--- a/src/pkg/debug/macho/file_test.go
+++ b/src/pkg/debug/macho/file_test.go
@@ -184,7 +184,7 @@ func TestOpenFat(t *testing.T) {
 		ftArch := &fileTests[i]
 
 		if arch.Cpu != ftArch.hdr.Cpu || arch.SubCpu != ftArch.hdr.SubCpu {
-			t.Error("OpenFat: architecture #%d got cpu=%#x subtype=%#x, expected cpu=%#x, subtype=%#x", i, arch.Cpu, arch.SubCpu, ftArch.hdr.Cpu, ftArch.hdr.SubCpu)
+			t.Errorf("OpenFat: architecture #%d got cpu=%#x subtype=%#x, expected cpu=%#x, subtype=%#x", i, arch.Cpu, arch.SubCpu, ftArch.hdr.Cpu, ftArch.hdr.SubCpu)
 		}
 
 		if !reflect.DeepEqual(arch.FileHeader, ftArch.hdr) {
@@ -202,9 +202,9 @@ func TestOpenFatFailure(t *testing.T) {
 	filename = "testdata/gcc-386-darwin-exec" // not a fat Mach-O
 	ff, err := OpenFat(filename)
 	if err != ErrNotFat {
-		t.Errorf("OpenFat %s: got %v, want ErrNotFat", err)
+		t.Errorf("OpenFat %s: got %v, want ErrNotFat", filename, err)
 	}
 	if ff != nil {
-		t.Errorf("OpenFat %s: got %v, want nil", ff)
+		t.Errorf("OpenFat %s: got %v, want nil", filename, ff)
 	}
 }
diff --git a/src/pkg/encoding/base64/base64_test.go b/src/pkg/encoding/base64/base64_test.go
index f1469c6842..a075194e03 100644
--- a/src/pkg/encoding/base64/base64_test.go
+++ b/src/pkg/encoding/base64/base64_test.go
@@ -336,7 +336,7 @@ func TestDecoderIssue7733(t *testing.T) {
 	s, err := StdEncoding.DecodeString("YWJjZA=====")
 	want := CorruptInputError(8)
 	if !reflect.DeepEqual(want, err) {
-		t.Errorf("Error = %v; want CorruptInputError(8)")
+		t.Errorf("Error = %v; want CorruptInputError(8)", err)
 	}
 	if string(s) != "abcd" {
 		t.Errorf("DecodeString = %q; want abcd", s)
diff --git a/src/pkg/html/template/escape.go b/src/pkg/html/template/escape.go
index 5f458d172d..4e379828d4 100644
--- a/src/pkg/html/template/escape.go
+++ b/src/pkg/html/template/escape.go
@@ -221,7 +221,6 @@ func allIdents(node parse.Node) []string {
 		return node.Ident
 	}
 	panic("unidentified node type in allIdents")
-	return nil
 }
 
 // ensurePipelineContains ensures that the pipeline has commands with
diff --git a/src/pkg/net/http/serve_test.go b/src/pkg/net/http/serve_test.go
index d9a136742c..030fd6e7b2 100644
--- a/src/pkg/net/http/serve_test.go
+++ b/src/pkg/net/http/serve_test.go
@@ -2325,7 +2325,7 @@ func TestServerConnState(t *testing.T) {
 	ts.Config.ErrorLog = log.New(ioutil.Discard, "", 0)
 	ts.Config.ConnState = func(c net.Conn, state ConnState) {
 		if c == nil {
-			t.Error("nil conn seen in state %s", state)
+			t.Errorf("nil conn seen in state %s", state)
 			return
 		}
 		mu.Lock()
diff --git a/src/pkg/net/http/transport_test.go b/src/pkg/net/http/transport_test.go
index ab459738df..a5aaa6bab8 100644
--- a/src/pkg/net/http/transport_test.go
+++ b/src/pkg/net/http/transport_test.go
@@ -1412,7 +1412,6 @@ func TestTransportCancelRequestInDial(t *testing.T) {
 	case <-gotres:
 	case <-time.After(5 * time.Second):
 		panic("hang. events are: " + logbuf.String())
-		t.Fatal("timeout; cancel didn't work?")
 	}
 
 	got := logbuf.String()
@@ -1869,10 +1868,10 @@ func TestTransportTLSHandshakeTimeout(t *testing.T) {
 			return
 		}
 		if !ne.Timeout() {
-			t.Error("expected timeout error; got %v", err)
+			t.Errorf("expected timeout error; got %v", err)
 		}
 		if !strings.Contains(err.Error(), "handshake timeout") {
-			t.Error("expected 'handshake timeout' in error; got %v", err)
+			t.Errorf("expected 'handshake timeout' in error; got %v", err)
 		}
 	}()
 	select {