diff --git a/src/cmd/go/get.go b/src/cmd/go/get.go
index 6ad683a8be..f70b6761de 100644
--- a/src/cmd/go/get.go
+++ b/src/cmd/go/get.go
@@ -252,7 +252,9 @@ func downloadPackage(p *Package) error {
 
 	if p.build.SrcRoot == "" {
 		// Package not found.  Put in first directory of $GOPATH or else $GOROOT.
-		if list := filepath.SplitList(buildContext.GOPATH); len(list) > 0 {
+		// Guard against people setting GOPATH=$GOROOT.  We have to use
+		// $GOROOT's directory hierarchy (src/pkg, not just src) in that case.
+		if list := filepath.SplitList(buildContext.GOPATH); len(list) > 0 && list[0] != goroot {
 			p.build.SrcRoot = filepath.Join(list[0], "src")
 			p.build.PkgRoot = filepath.Join(list[0], "pkg")
 		} else {
diff --git a/src/cmd/go/main.go b/src/cmd/go/main.go
index 2f8209c86f..73c2f54a76 100644
--- a/src/cmd/go/main.go
+++ b/src/cmd/go/main.go
@@ -16,6 +16,7 @@ import (
 	"path"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"strings"
 	"sync"
 	"text/template"
@@ -121,6 +122,13 @@ func main() {
 		return
 	}
 
+	// Diagnose common mistake: GOPATH==GOROOT.
+	// This setting is equivalent to not setting GOPATH at all,
+	// which is not what most people want when they do it.
+	if gopath := os.Getenv("GOPATH"); gopath == runtime.GOROOT() {
+		fmt.Fprintf(os.Stderr, "warning: GOPATH set to GOROOT (%s) has no effect\n", gopath)
+	}
+
 	for _, cmd := range commands {
 		if cmd.Name() == args[0] && cmd.Run != nil {
 			cmd.Flag.Usage = func() { cmd.Usage() }
diff --git a/src/cmd/go/pkg.go b/src/cmd/go/pkg.go
index 44dbd6798a..1a75019aca 100644
--- a/src/cmd/go/pkg.go
+++ b/src/cmd/go/pkg.go
@@ -217,7 +217,10 @@ func loadImport(path string, srcDir string, stk *importStack, importPos []token.
 	// Load package.
 	// Import always returns bp != nil, even if an error occurs,
 	// in order to return partial information.
-	bp, err := buildContext.Import(path, srcDir, build.AllowBinary)
+	//
+	// TODO: After Go 1, decide when to pass build.AllowBinary here.
+	// See issue 3268 for mistakes to avoid.
+	bp, err := buildContext.Import(path, srcDir, 0)
 	bp.ImportPath = importPath
 	p.load(stk, bp, err)
 	if p.Error != nil && len(importPos) > 0 {