diff --git a/common/include/villas/list.h b/common/include/villas/list.h
index a00dbecef..7838e01d4 100644
--- a/common/include/villas/list.h
+++ b/common/include/villas/list.h
@@ -42,11 +42,11 @@ __attribute__((constructor(105))) static void UNIQUE(__ctor)() {\
 		vlist_init(l);					\
 }								\
 __attribute__((destructor(105))) static void UNIQUE(__dtor)() {	\
-	vlist_destroy(l, NULL, false);				\
+	vlist_destroy(l, nullptr, false);				\
 }
 
 #define vlist_length(list)		((list)->length)
-#define vlist_at_safe(list, index)	((list)->length > index ? (list)->array[index] : NULL)
+#define vlist_at_safe(list, index)	((list)->length > index ? (list)->array[index] : nullptr)
 #define vlist_at(list, index)		((list)->array[index])
 
 #define vlist_first(list)		vlist_at(list, 0)