diff --git a/Foundation/CPKeyValueObserving.j b/Foundation/CPKeyValueObserving.j
index 83f55b773..a7994f164 100644
--- a/Foundation/CPKeyValueObserving.j
+++ b/Foundation/CPKeyValueObserving.j
@@ -344,7 +344,7 @@ var kvoNewAndOld = CPKeyValueObservingOptionNew | CPKeyValueObservingOptionOld,
         insertObject_inKeyAtIndex_method =
             class_getInstanceMethod(theClass, insertObject_inKeyAtIndex_selector),
 
-        insertKey_atIndexes_selector = sel_getUid("insert" + capitalizedKey + ":atIndex:"),
+        insertKey_atIndexes_selector = sel_getUid("insert" + capitalizedKey + ":atIndexes:"),
         insertKey_atIndexes_method =
             class_getInstanceMethod(theClass, insertKey_atIndexes_selector),