diff --git a/misc/cgo/test/backdoor.go b/misc/cgo/test/backdoor.go
new file mode 100644
index 00000000000..6fb33d66cb2
--- /dev/null
+++ b/misc/cgo/test/backdoor.go
@@ -0,0 +1,11 @@
+// Copyright 2014 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 cgotest
+
+import _ "unsafe"
+
+//go:linkname lockedOSThread runtime.lockedOSThread
+//extern runtime_lockedOSThread
+func lockedOSThread() bool
diff --git a/misc/cgo/test/backdoor/backdoor.go b/misc/cgo/test/backdoor/backdoor.go
deleted file mode 100644
index 27b71b1f572..00000000000
--- a/misc/cgo/test/backdoor/backdoor.go
+++ /dev/null
@@ -1,7 +0,0 @@
-// Copyright 2012 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 backdoor
-
-func LockedOSThread() bool // in thunk.s or runtime_gccgo.c
diff --git a/misc/cgo/test/backdoor/runtime_gccgo.c b/misc/cgo/test/backdoor/runtime_gccgo.c
deleted file mode 100644
index b75f47b92d4..00000000000
--- a/misc/cgo/test/backdoor/runtime_gccgo.c
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2012 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.
-
-// Expose some runtime functions for testing.
-// This is the gccgo version of thunk.s.
-
-// +build gccgo
-
-_Bool runtime_lockedOSThread(void);
-
-_Bool LockedOSThread(void) asm(GOPKGPATH ".LockedOSThread");
-
-_Bool
-LockedOSThread(void)
-{
-	return runtime_lockedOSThread();
-}
diff --git a/misc/cgo/test/backdoor/thunk.s b/misc/cgo/test/backdoor/thunk.s
deleted file mode 100644
index 8240faf63b7..00000000000
--- a/misc/cgo/test/backdoor/thunk.s
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2014 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.
-
-// Assembly to get into package runtime without using exported symbols.
-
-// +build amd64 amd64p32 arm 386
-// +build gc
-
-#include "textflag.h"
-
-#ifdef GOARCH_arm
-#define JMP B
-#endif
-
-TEXT ·LockedOSThread(SB),NOSPLIT,$0-0
-	JMP	runtime·lockedOSThread(SB)
diff --git a/misc/cgo/test/callback.go b/misc/cgo/test/callback.go
index 44167e6e9ef..6e1e5569fca 100644
--- a/misc/cgo/test/callback.go
+++ b/misc/cgo/test/callback.go
@@ -22,8 +22,6 @@ import (
 	"strings"
 	"testing"
 	"unsafe"
-
-	"./backdoor"
 )
 
 // nestedCall calls into C, back into Go, and finally to f.
@@ -50,8 +48,6 @@ func testCallbackGC(t *testing.T) {
 	nestedCall(runtime.GC)
 }
 
-var lockedOSThread = backdoor.LockedOSThread
-
 func testCallbackPanic(t *testing.T) {
 	// Make sure panic during callback unwinds properly.
 	if lockedOSThread() {