diff --git a/AFNetworking/AFHTTPClient.m b/AFNetworking/AFHTTPClient.m
index 8795ae3..bf26305 100644
--- a/AFNetworking/AFHTTPClient.m
+++ b/AFNetworking/AFHTTPClient.m
@@ -304,7 +304,8 @@ static void AFNetworkReachabilityCallback(SCNetworkReachabilityRef __unused targ
     }
 
     dispatch_async(dispatch_get_main_queue(), ^{
-        [[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingReachabilityDidChangeNotification object:nil userInfo:[NSDictionary dictionaryWithObject:[NSNumber numberWithInteger:status] forKey:AFNetworkingReachabilityNotificationStatusItem]];
+        NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
+        [notificationCenter postNotificationName:AFNetworkingReachabilityDidChangeNotification object:nil userInfo:[NSDictionary dictionaryWithObject:[NSNumber numberWithInteger:status] forKey:AFNetworkingReachabilityNotificationStatusItem]];
     });
 }
 
diff --git a/AFNetworking/AFURLConnectionOperation.m b/AFNetworking/AFURLConnectionOperation.m
index 122ec36..bb8bf55 100644
--- a/AFNetworking/AFURLConnectionOperation.m
+++ b/AFNetworking/AFURLConnectionOperation.m
@@ -341,12 +341,13 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     [self.lock unlock];
 
     dispatch_async(dispatch_get_main_queue(), ^{
+        NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
         switch (state) {
             case AFOperationExecutingState:
-                [[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingOperationDidStartNotification object:self];
+                [notificationCenter postNotificationName:AFNetworkingOperationDidStartNotification object:self];
                 break;
             case AFOperationFinishedState:
-                [[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingOperationDidFinishNotification object:self];
+                [notificationCenter postNotificationName:AFNetworkingOperationDidFinishNotification object:self];
                 break;
             default:
                 break;
@@ -393,7 +394,8 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
         [self.connection performSelector:@selector(cancel) onThread:[[self class] networkRequestThread] withObject:nil waitUntilDone:NO modes:[self.runLoopModes allObjects]];
 
         dispatch_async(dispatch_get_main_queue(), ^{
-            [[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingOperationDidFinishNotification object:self];
+            NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
+            [notificationCenter postNotificationName:AFNetworkingOperationDidFinishNotification object:self];
         });
     }