diff --git a/src/cmd/hgpatch/main.go b/src/cmd/hgpatch/main.go
index 282122daa53..3d18971cf7b 100644
--- a/src/cmd/hgpatch/main.go
+++ b/src/cmd/hgpatch/main.go
@@ -346,12 +346,12 @@ func run(argv []string, input []byte) (out string, err os.Error) {
 	// fmt.Fprintf(os.Stderr, "%v\n", argv);
 	var cmd *exec.Cmd
 	if len(input) == 0 {
-		cmd, err = exec.Run(prog, argv, os.Environ(), exec.DevNull, exec.Pipe, exec.MergeWithStdout)
+		cmd, err = exec.Run(prog, argv, os.Environ(), "", exec.DevNull, exec.Pipe, exec.MergeWithStdout)
 		if err != nil {
 			goto Error
 		}
 	} else {
-		cmd, err = exec.Run(prog, argv, os.Environ(), exec.Pipe, exec.Pipe, exec.MergeWithStdout)
+		cmd, err = exec.Run(prog, argv, os.Environ(), "", exec.Pipe, exec.Pipe, exec.MergeWithStdout)
 		if err != nil {
 			goto Error
 		}
diff --git a/src/pkg/exec/exec.go b/src/pkg/exec/exec.go
index 8e959e03a3e..a1b7bd6b9c0 100644
--- a/src/pkg/exec/exec.go
+++ b/src/pkg/exec/exec.go
@@ -78,7 +78,7 @@ func modeToFiles(mode, fd int) (*os.File, *os.File, os.Error) {
 // If a parameter is Pipe, then the corresponding field (Stdin, Stdout, Stderr)
 // of the returned Cmd is the other end of the pipe.
 // Otherwise the field in Cmd is nil.
-func Run(argv0 string, argv, envv []string, stdin, stdout, stderr int) (p *Cmd, err os.Error) {
+func Run(argv0 string, argv, envv []string, dir string, stdin, stdout, stderr int) (p *Cmd, err os.Error) {
 	p = new(Cmd)
 	var fd [3]*os.File
 
@@ -89,13 +89,13 @@ func Run(argv0 string, argv, envv []string, stdin, stdout, stderr int) (p *Cmd,
 		goto Error
 	}
 	if stderr == MergeWithStdout {
-		p.Stderr = p.Stdout
+		fd[2] = fd[1]
 	} else if fd[2], p.Stderr, err = modeToFiles(stderr, 2); err != nil {
 		goto Error
 	}
 
 	// Run command.
-	p.Pid, err = os.ForkExec(argv0, argv, envv, "", &fd)
+	p.Pid, err = os.ForkExec(argv0, argv, envv, dir, &fd)
 	if err != nil {
 		goto Error
 	}
diff --git a/src/pkg/exec/exec_test.go b/src/pkg/exec/exec_test.go
index 9c4d2ee319a..3e4ab7d7800 100644
--- a/src/pkg/exec/exec_test.go
+++ b/src/pkg/exec/exec_test.go
@@ -11,39 +11,76 @@ import (
 )
 
 func TestRunCat(t *testing.T) {
-	cmd, err := Run("/bin/cat", []string{"cat"}, nil,
+	cmd, err := Run("/bin/cat", []string{"cat"}, nil, "",
 		Pipe, Pipe, DevNull)
 	if err != nil {
-		t.Fatalf("opencmd /bin/cat: %v", err)
+		t.Fatal("run:", err)
 	}
 	io.WriteString(cmd.Stdin, "hello, world\n")
 	cmd.Stdin.Close()
 	buf, err := ioutil.ReadAll(cmd.Stdout)
 	if err != nil {
-		t.Fatalf("reading from /bin/cat: %v", err)
+		t.Fatal("read:", err)
 	}
 	if string(buf) != "hello, world\n" {
-		t.Fatalf("reading from /bin/cat: got %q", buf)
+		t.Fatalf("read: got %q", buf)
 	}
 	if err = cmd.Close(); err != nil {
-		t.Fatalf("closing /bin/cat: %v", err)
+		t.Fatal("close:", err)
 	}
 }
 
 func TestRunEcho(t *testing.T) {
-	cmd, err := Run("/bin/echo", []string{"echo", "hello", "world"}, nil,
+	cmd, err := Run("/bin/echo", []string{"echo", "hello", "world"}, nil, "",
 		DevNull, Pipe, DevNull)
 	if err != nil {
-		t.Fatalf("opencmd /bin/echo: %v", err)
+		t.Fatal("run:", err)
 	}
 	buf, err := ioutil.ReadAll(cmd.Stdout)
 	if err != nil {
-		t.Fatalf("reading from /bin/echo: %v", err)
+		t.Fatal("read:", err)
 	}
 	if string(buf) != "hello world\n" {
-		t.Fatalf("reading from /bin/echo: got %q", buf)
+		t.Fatalf("read: got %q", buf)
 	}
 	if err = cmd.Close(); err != nil {
-		t.Fatalf("closing /bin/echo: %v", err)
+		t.Fatal("close:", err)
+	}
+}
+
+func TestStderr(t *testing.T) {
+	cmd, err := Run("/bin/sh", []string{"sh", "-c", "echo hello world 1>&2"}, nil, "",
+		DevNull, DevNull, Pipe)
+	if err != nil {
+		t.Fatal("run:", err)
+	}
+	buf, err := ioutil.ReadAll(cmd.Stderr)
+	if err != nil {
+		t.Fatal("read:", err)
+	}
+	if string(buf) != "hello world\n" {
+		t.Fatalf("read: got %q", buf)
+	}
+	if err = cmd.Close(); err != nil {
+		t.Fatal("close:", err)
+	}
+}
+
+
+func TestMergeWithStdout(t *testing.T) {
+	cmd, err := Run("/bin/sh", []string{"sh", "-c", "echo hello world 1>&2"}, nil, "",
+		DevNull, Pipe, MergeWithStdout)
+	if err != nil {
+		t.Fatal("run:", err)
+	}
+	buf, err := ioutil.ReadAll(cmd.Stdout)
+	if err != nil {
+		t.Fatal("read:", err)
+	}
+	if string(buf) != "hello world\n" {
+		t.Fatalf("read: got %q", buf)
+	}
+	if err = cmd.Close(); err != nil {
+		t.Fatal("close:", err)
 	}
 }