--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -544,16 +544,18 @@ nsHttpHandler::GetCookieService()
         mCookieService = new nsMainThreadPtrHolder<nsICookieService>(service);
     }
     return mCookieService;
 }
 
 nsresult
 nsHttpHandler::GetIOService(nsIIOService** result)
 {
+    NS_ENSURE_ARG_POINTER(result);
+
     NS_ADDREF(*result = mIOService);
     return NS_OK;
 }
 
 uint32_t
 nsHttpHandler::Get32BitsOfPseudoRandom()
 {
     // only confirm rand seeding on socket thread