diff --git a/src/pkg/runtime/race.c b/src/pkg/runtime/race.c
index 8f611cb2d8..17573a6978 100644
--- a/src/pkg/runtime/race.c
+++ b/src/pkg/runtime/race.c
@@ -87,10 +87,10 @@ runtime·raceread(uintptr addr)
 	}
 }
 
-// Called from instrumented code.
+// Called from runtime·racefuncenter (assembly).
 #pragma textflag 7
 void
-runtime·racefuncenter(uintptr pc)
+runtime·racefuncenter1(uintptr pc)
 {
 	// If the caller PC is lessstack, use slower runtime·callers
 	// to walk across the stack split to find the real caller.
diff --git a/src/pkg/runtime/race_amd64.s b/src/pkg/runtime/race_amd64.s
new file mode 100644
index 0000000000..0c6aaaa611
--- /dev/null
+++ b/src/pkg/runtime/race_amd64.s
@@ -0,0 +1,11 @@
+// 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.
+
+// +build race
+
+TEXT	runtime·racefuncenter(SB),7,$0
+	PUSHQ	DX // save function entry context (for closures)
+	CALL	runtime·racefuncenter1(SB)
+	POPQ	DX
+	RET