diff --git a/Foundation/CPKeyValueObserving.j b/Foundation/CPKeyValueObserving.j
index 1115d8cd9..308cb0f6e 100644
--- a/Foundation/CPKeyValueObserving.j
+++ b/Foundation/CPKeyValueObserving.j
@@ -1003,7 +1003,7 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
 @end
 
-@implementation _CPKVOModelSubclass
+@implementation _CPKVOModelSubclass : CPObject
 {
 }
 
@@ -1129,7 +1129,7 @@ var kvoNewAndOld        = CPKeyValueObservingOptionNew | CPKeyValueObservingOpti
 
 @end
 
-@implementation _CPKVOModelDictionarySubclass
+@implementation _CPKVOModelDictionarySubclass : CPObject
 {
 }