diff --git a/include/ucore/ucore_utils.h b/include/ucore/ucore_utils.h
index fc389cc..c76499b 100644
--- a/include/ucore/ucore_utils.h
+++ b/include/ucore/ucore_utils.h
@@ -47,7 +47,7 @@
 //struct foo *f = CONTAINER_OF(p, struct foo, zap);
 #define CONTAINER_OF(ptr, type, member) ({                  \
 typeof( ((type *)0)->member ) *__mptr = (ptr);    \
-    (type *)( (char *)__mptr - offsetof(type, member) ); })
+    (type *)( (void *)__mptr - offsetof(type, member) ); })
 
 #define UC_ALIGN(val,align) (((val)+(align)-1UL)&~((align)-1UL))