diff --git a/AFNetworking/AFURLConnectionOperation.m b/AFNetworking/AFURLConnectionOperation.m
index f768816..04e9e52 100644
--- a/AFNetworking/AFURLConnectionOperation.m
+++ b/AFNetworking/AFURLConnectionOperation.m
@@ -630,6 +630,8 @@ willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challe
                 break;
             }
         }
+    } else if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodDefault]) {
+        [[challenge sender] performDefaultHandlingForAuthenticationChallenge:challenge];
     }
 }
 #endif