diff --git a/src/xpdev/str_list.h b/src/xpdev/str_list.h
index ebf8d72d1725afabcc291714eb0efdba38d181e3..20e0338a95fa2d0ecd28119bfb08622b2e18341b 100644
--- a/src/xpdev/str_list.h
+++ b/src/xpdev/str_list.h
@@ -39,6 +39,7 @@
 #define _STR_LIST_H
 
 #include <stdio.h>			/* FILE */
+#include <stddef.h>         /* size_t */
 #include "gen_defs.h"
 
 #if defined(__cplusplus)