diff --git a/src/kernel_win/rbtree.h b/src/kernel_win/rbtree.h
index c863195b..35bf725c 100644
--- a/src/kernel_win/rbtree.h
+++ b/src/kernel_win/rbtree.h
@@ -115,7 +115,7 @@ struct rb_root
 
 #define RB_ROOT (struct rb_root){ (struct rb_node *)0, }
 #define	rb_entry(ptr, type, member) \
-	((type *)((char *)(ptr) - offsetof(type, member)))
+	((type *)((char *)(ptr)-(size_t)(&((type *)0)->member)))
 
 #ifdef __cplusplus
 extern "C"