diff --git a/x11-wm/windowmaker/Makefile b/x11-wm/windowmaker/Makefile
index 9dd70361ed41..1a402a704cdb 100644
--- a/x11-wm/windowmaker/Makefile
+++ b/x11-wm/windowmaker/Makefile
@@ -25,6 +25,7 @@ LIB_DEPENDS=	libgif.so:graphics/giflib \
 RUN_DEPENDS=	${LOCALBASE}/share/WindowMaker/Themes/LeetWM.themed/style:graphics/wmicons
 
 USES=		gnome jpeg libtool shebangfix pathfix perl5 pkgconfig xorg
+USE_CSTD=	c99
 USE_GNOME=	pango
 USE_LDCONFIG=	yes
 USE_XORG=	x11 xext xft xinerama xmu xpm