Use full import paths for test protos.
diff --git a/proto/clone_test.go b/proto/clone_test.go
index 1ac177d..9db0fb6 100644
--- a/proto/clone_test.go
+++ b/proto/clone_test.go
@@ -36,7 +36,7 @@
 
 	"github.com/golang/protobuf/proto"
 
-	pb "./testdata"
+	pb "github.com/golang/protobuf/proto/testdata"
 )
 
 var cloneTestMessage = &pb.MyMessage{