diff --git a/src/net/http/cookie_test.go b/src/net/http/cookie_test.go
index 98dc2fade0..1ec993e935 100644
--- a/src/net/http/cookie_test.go
+++ b/src/net/http/cookie_test.go
@@ -349,7 +349,7 @@ func TestSetCookieDoubleQuotes(t *testing.T) {
 		{Name: "quoted3", Value: "both"},
 	}
 	if len(got) != len(want) {
-		t.Fatal("got %d cookies, want %d", len(got), len(want))
+		t.Fatalf("got %d cookies, want %d", len(got), len(want))
 	}
 	for i, w := range want {
 		g := got[i]