diff --git a/code/ryzom/tools/sheets_packer/stdpch.h b/code/ryzom/tools/sheets_packer/stdpch.h
index d0135ae17..afa7d2137 100644
--- a/code/ryzom/tools/sheets_packer/stdpch.h
+++ b/code/ryzom/tools/sheets_packer/stdpch.h
@@ -1,5 +1,6 @@
 #include <nel/misc/types_nl.h>
 
+#include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>