diff --git a/lib/roken/parse_units.h b/lib/roken/parse_units.h
index 4544767fa..a56533b2e 100644
--- a/lib/roken/parse_units.h
+++ b/lib/roken/parse_units.h
@@ -41,7 +41,7 @@
 #ifndef __PARSE_UNITS_H__
 #define __PARSE_UNITS_H__
 
-#include <stdlib.h>
+#include <stddef.h>
 
 struct units {
     const char *name;