diff --git a/tools/editworld/src/listtemp.h b/tools/editworld/src/listtemp.h
index 8f1e02854..32688ae27 100644
--- a/tools/editworld/src/listtemp.h
+++ b/tools/editworld/src/listtemp.h
@@ -25,6 +25,8 @@
 #ifndef __INCLUDED_LISTTEMP__
 #define __INCLUDED_LISTTEMP__
 
+#include <cassert>
+
 template<class T>
 class ListNode
 {