diff --git a/container/intsets/popcnt_gccgo.go b/container/intsets/popcnt_gccgo.go
new file mode 100644
index 0000000000..82a8875c85
--- /dev/null
+++ b/container/intsets/popcnt_gccgo.go
@@ -0,0 +1,9 @@
+// Copyright 2015 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 gccgo
+
+package intsets
+
+func popcount(x word) int
diff --git a/container/intsets/popcnt_gccgo_c.c b/container/intsets/popcnt_gccgo_c.c
new file mode 100644
index 0000000000..08abb32ec4
--- /dev/null
+++ b/container/intsets/popcnt_gccgo_c.c
@@ -0,0 +1,19 @@
+// Copyright 2015 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 gccgo
+
+#include <errno.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#define _STRINGIFY2_(x) #x
+#define _STRINGIFY_(x) _STRINGIFY2_(x)
+#define GOSYM_PREFIX _STRINGIFY_(__USER_LABEL_PREFIX__)
+
+extern intptr_t popcount(uintptr_t x) __asm__(GOSYM_PREFIX GOPKGPATH ".popcount");
+
+intptr_t popcount(uintptr_t x) {
+	return __builtin_popcountl((unsigned long)(x));
+}
diff --git a/container/intsets/popcnt_generic.go b/container/intsets/popcnt_generic.go
index 682e2f53a4..3985a1da1a 100644
--- a/container/intsets/popcnt_generic.go
+++ b/container/intsets/popcnt_generic.go
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64 appengine gccgo
+// +build !amd64 appengine
+// +build !gccgo
 
 package intsets