diff --git a/embedding/components/windowwatcher/public/nsPromptUtils.h b/embedding/components/windowwatcher/public/nsPromptUtils.h
index fd73289f9fe8..b4f9fce05825 100644
--- a/embedding/components/windowwatcher/public/nsPromptUtils.h
+++ b/embedding/components/windowwatcher/public/nsPromptUtils.h
@@ -103,7 +103,7 @@ NS_GetAuthHostPort(nsIChannel* aChannel, nsIAuthInformation* aAuthInfo,
 
     nsCOMPtr<nsIProxyInfo> info;
     proxied->GetProxyInfo(getter_AddRefs(info));
-    NS_ASSERTION(proxied, "proxy auth needs nsIProxyInfo");
+    NS_ASSERTION(info, "proxy auth needs nsIProxyInfo");
 
     nsCAutoString idnhost;
     info->GetHost(idnhost);