diff --git a/AFNetworking/AFURLSessionManager.m b/AFNetworking/AFURLSessionManager.m
index 837ea1cffc..63b0042365 100644
--- a/AFNetworking/AFURLSessionManager.m
+++ b/AFNetworking/AFURLSessionManager.m
@@ -284,7 +284,7 @@ @interface NSURLSessionTask (_AFStateObserving)
 @implementation NSURLSessionTask (_AFStateObserving)
 
 + (void)initialize {
-    if ([NSURLSessionTask class]) {
+    if ([NSStringFromClass([self class]) isEqualToString:NSStringFromClass([NSURLSessionTask class])]) {
         NSURLSessionDataTask *dataTask = [[NSURLSession sessionWithConfiguration:nil] dataTaskWithURL:nil];
         Class taskClass = [dataTask superclass];