diff --git a/quark-shell/QSHWebViewDelegate.m b/quark-shell/QSHWebViewDelegate.m
index 4c92bd8..a1cdfbd 100644
--- a/quark-shell/QSHWebViewDelegate.m
+++ b/quark-shell/QSHWebViewDelegate.m
@@ -417,7 +417,7 @@ - (void)subscribeMessage:(NSString *)name withCallback:(WebScriptObject *)callba
         [self.messageSubscribers[name] addObject:callback];
     }
     else {
-        self.messageSubscribers[name] = @[callback];
+        self.messageSubscribers[name] = [NSMutableArray arrayWithObject:callback];
     }
 }