diff --git a/src/pkg/mime/multipart/writer_test.go b/src/pkg/mime/multipart/writer_test.go
index 2412985b9bb..ba00c97ecee 100644
--- a/src/pkg/mime/multipart/writer_test.go
+++ b/src/pkg/mime/multipart/writer_test.go
@@ -118,8 +118,11 @@ func TestWriterBoundaryGoroutines(t *testing.T) {
 	// https://codereview.appspot.com/95760043/ and reverted in
 	// https://codereview.appspot.com/117600043/
 	w := NewWriter(ioutil.Discard)
+	done := make(chan int)
 	go func() {
 		w.CreateFormField("foo")
+		done <- 1
 	}()
 	w.Boundary()
+	<-done
 }