diff --git a/core.h b/core.h
index 06cbe9a..8173228 100644
--- a/core.h
+++ b/core.h
@@ -153,9 +153,9 @@ DefineList(string, String);
     if ((list)->length < (list)->capacity) { \
         (list)->data[(list)->length++] = (element); \
     }
-#define ZeroListFull(list) memset((list)->data, 0, (list)->length * sizeof(T))
+#define ZeroListFull(list) memset((list)->data, 0, (list)->length * MemberTypeUnderlying(typeof(list), data))
 #define ZeroList(list) (list)->length = 0; \
-    memset((list)->data, 0, (list)->length * sizeof(T));
+    memset((list)->data, 0, (list)->length * MemberTypeUnderlying(typeof(list), data));
 #define ListSlice(list, start, stop) (stop > list.length || start > stop ? {0} : { list.data + start, stop - start, stop - start, })
 #define ListTail(list, start) ListSlice(list, list.length)