diff --git a/src/pkg/runtime/export_test.go b/src/pkg/runtime/export_test.go
--- a/src/pkg/runtime/export_test.go
+++ b/src/pkg/runtime/export_test.go
@@ -68,12 +68,14 @@
 var TestSchedLocalQueue1 = testSchedLocalQueue
 var TestSchedLocalQueueSteal1 = testSchedLocalQueueSteal
 
+func analizeStack(t uintptr, fn func(uintptr))
 func haveGoodHash() bool
 func stringHash(s string, seed uintptr) uintptr
 func bytesHash(b []byte, seed uintptr) uintptr
 func int32Hash(i uint32, seed uintptr) uintptr
 func int64Hash(i uint64, seed uintptr) uintptr
 
+var AnalizeStack = analizeStack
 var HaveGoodHash = haveGoodHash
 var StringHash = stringHash
 var BytesHash = bytesHash
diff --git a/src/pkg/runtime/goroot_test.c b/src/pkg/runtime/goroot_test.c
new file mode 100644
--- /dev/null
+++ b/src/pkg/runtime/goroot_test.c
@@ -0,0 +1,14 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "arch_GOARCH.h"
+
+// For testing from Go
+// func analizeStack(uintptr t, fn func(uintptr))
+void
+runtime·analizeStack(uintptr t, void *fn)
+{
+	(*(void(**)(uintptr))fn)(t);
+}
diff --git a/src/pkg/runtime/goroot_test.go b/src/pkg/runtime/goroot_test.go
new file mode 100644
--- /dev/null
+++ b/src/pkg/runtime/goroot_test.go
@@ -0,0 +1,81 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"flag"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"unsafe"
+)
+
+var sympathprefix = flag.String("sympathprefix", "", "param for TestSymPathPrefix")
+
+// TODO: only checks .go and .c files (need also verify .s files)
+func testSymPathPrefix(p uintptr) {
+	t := (*testing.T)(unsafe.Pointer(p))
+	todir := func(pkg string) string {
+		d := filepath.Join(*sympathprefix, "src", "pkg", pkg)
+		return filepath.ToSlash(d)
+	}
+	rdir := todir("runtime")
+	tdir := todir("testing")
+	for i := 0; ; i++ {
+		_, file, _, ok := runtime.Caller(i)
+		if !ok {
+			break
+		}
+		switch filepath.ToSlash(filepath.Dir(file)) {
+		case rdir, tdir:
+			continue
+		}
+		t.Errorf("wrong dir in %v (%v or %v expected)", file, rdir, tdir)
+	}
+}
+
+func TestSymPathPrefix(t *testing.T) {
+	runtime.AnalizeStack(uintptr(unsafe.Pointer(t)), testSymPathPrefix)
+}
+
+func setEnv(env []string, name, value string) []string {
+	for i, e := range env {
+		if strings.HasPrefix(e, name+"=") {
+			env[i] = name + "=" + value
+			return env
+		}
+	}
+	return append(env, name+"="+value)
+}
+
+func testALEX(t *testing.T, sympathprefix string, env []string) {
+	obj := filepath.Join(runtime.GOROOT(), "pkg", runtime.GOOS+"_"+runtime.GOARCH, "runtime.a")
+	os.Remove(obj)
+	cmd := exec.Command("go", "install", "runtime")
+	cmd.Env = env
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go install failed: err=%v output=%s", err, out)
+	}
+	defer os.Remove(obj)
+	cmd = exec.Command("go", "test", "-v", "-sympathprefix="+sympathprefix, "-run=TestSymPathPrefix", "runtime")
+	cmd.Env = env
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go test failed: err=%v output=%s", err, out)
+	}
+}
+
+func TestALEX(t *testing.T) {
+	final := "/final"
+	if runtime.GOOS == "windows" {
+		final = `c:\final`
+	}
+	testALEX(t, final, setEnv(os.Environ(), "GOROOT_FINAL", final))
+	testALEX(t, runtime.GOROOT(), os.Environ())
+}