diff --git a/html5/verto/js/src/jquery.verto.js b/html5/verto/js/src/jquery.verto.js
index a2e02e4bdc..7e19c90343 100644
--- a/html5/verto/js/src/jquery.verto.js
+++ b/html5/verto/js/src/jquery.verto.js
@@ -613,7 +613,9 @@
                 break;
 
             case 'verto.clientReady':
-                verto.callbacks.onMessage(verto, null, $.verto.enum.message.clientReady, data.params);
+                if (verto.callbacks.onMessage) {
+                    verto.callbacks.onMessage(verto, null, $.verto.enum.message.clientReady, data.params);
+                }
                 console.debug("CLIENT READY", data.params);
                 break;