diff --git a/Foundation/CPArray+KVO.j b/Foundation/CPArray+KVO.j
index 64ccd2a8f..f9685ce47 100644
--- a/Foundation/CPArray+KVO.j
+++ b/Foundation/CPArray+KVO.j
@@ -447,7 +447,7 @@ kvoOperators["sum"] = function sumOperator(self, _cmd, param)
 
 -(void)addObserver:(id)observer forKeyPath:(CPString)aKeyPath options:(unsigned)options context:(id)context
 {
-    if ([isa instanceMethodForSelector:_cmd]==[NSArray instanceMethodForSelector:_cmd])
+    if ([isa instanceMethodForSelector:_cmd] === [CPArray instanceMethodForSelector:_cmd])
         [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
     else
         [super addObserver:observer forKeyPath:aKeyPath options:options context:context];
@@ -455,7 +455,7 @@ kvoOperators["sum"] = function sumOperator(self, _cmd, param)
 
 -(void)removeObserver:(id)observer forKeyPath:(CPString)aKeyPath
 {
-    if ([isa instanceMethodForSelector:_cmd]==[NSArray instanceMethodForSelector:_cmd])
+    if ([isa instanceMethodForSelector:_cmd] === [CPArray instanceMethodForSelector:_cmd])
         [CPException raise:CPInvalidArgumentException reason:"Unsupported method on CPArray"];
     else
         [super removeObserver:observer forKeyPath:aKeyPath];