diff --git a/RxCocoa/Common/_RXDelegateProxy.m b/RxCocoa/Common/_RXDelegateProxy.m
index 581fbabb..c82333a0 100644
--- a/RxCocoa/Common/_RXDelegateProxy.m
+++ b/RxCocoa/Common/_RXDelegateProxy.m
@@ -58,7 +58,7 @@ static NSMutableDictionary *forwardableSelectorsPerClass = nil;
 #define CLASS_HIERARCHY_MAX_DEPTH 100
 
         NSInteger  classHierarchyDepth = 0;
-        Class      targetClass         = self;
+        Class      targetClass         = NULL;
 
         for (classHierarchyDepth = 0, targetClass = self;
              classHierarchyDepth < CLASS_HIERARCHY_MAX_DEPTH && targetClass != nil;