diff --git a/src/pkg/os/user/lookup_stubs.go b/src/pkg/os/user/lookup_stubs.go
index 7fc087c4dc..ea01f9683d 100644
--- a/src/pkg/os/user/lookup_stubs.go
+++ b/src/pkg/os/user/lookup_stubs.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build netbsd openbsd plan9 windows
+// +build nocgo
 
 package user
 
diff --git a/src/pkg/os/user/lookup_unix.go b/src/pkg/os/user/lookup_unix.go
index a77aeb73bb..21c8346b2f 100644
--- a/src/pkg/os/user/lookup_unix.go
+++ b/src/pkg/os/user/lookup_unix.go
@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build darwin freebsd linux
+// +build cgo
 
 package user