diff --git a/tests/cefclient/cefclient_mac.mm b/tests/cefclient/cefclient_mac.mm
index f2a77bc6a..7c487adbb 100644
--- a/tests/cefclient/cefclient_mac.mm
+++ b/tests/cefclient/cefclient_mac.mm
@@ -122,7 +122,7 @@ const int kWindowHeight = 600;
                                    defaultButton:@"OK"
                                  alternateButton:nil
                                      otherButton:nil
-                       informativeTextWithFormat:message];
+                       informativeTextWithFormat:@"%@", message];
   [alert runModal];
 }