diff --git a/Source/NSObjCRuntime.m b/Source/NSObjCRuntime.m
index 048c10269..4a5af4fd5 100644
--- a/Source/NSObjCRuntime.m
+++ b/Source/NSObjCRuntime.m
@@ -128,7 +128,8 @@ GSGetInstanceVariable(id obj, NSString *iVarName, void *data)
     {
       return NO;
     }
-
+  //This very highly unprobable value can be used as a marker
+  NSAssert(offset!=UINT_MAX,@"Bad Offset");
   memcpy(data, ((void*)obj) + offset, size);
   return YES;
 }
@@ -144,6 +145,8 @@ GSSetInstanceVariable(id obj, NSString *iVarName, const void *data)
     {
       return NO;
     }
+  //This very highly unprobable value can be used as a marker
+  NSAssert(offset!=UINT_MAX,@"Bad Offset");
   memcpy(((void*)obj) + offset, data, size);
   return YES;
 }