--- a/netwerk/base/nsIOService.cpp
+++ b/netwerk/base/nsIOService.cpp
@@ -1820,16 +1820,18 @@ IOServiceProxyCallback::OnProxyAvailable
 }
 
 nsresult
 nsIOService::SpeculativeConnectInternal(nsIURI *aURI,
                                         nsIPrincipal *aPrincipal,
                                         nsIInterfaceRequestor *aCallbacks,
                                         bool aAnonymous)
 {
+    NS_ENSURE_ARG(aURI);
+
     bool isHTTP, isHTTPS;
     if (!(NS_SUCCEEDED(aURI->SchemeIs("http", &isHTTP)) && isHTTP) &&
         !(NS_SUCCEEDED(aURI->SchemeIs("https", &isHTTPS)) && isHTTPS)) {
         // We don't speculatively connect to non-HTTP[S] URIs.
         return NS_OK;
     }
 
     if (IsNeckoChild()) {