Index: head/lang/python35/Makefile
===================================================================
--- head/lang/python35/Makefile
+++ head/lang/python35/Makefile
@@ -16,6 +16,7 @@
 LICENSE=	PSFL
 
 USES=		cpe ncurses pathfix pkgconfig readline:port shebangfix ssl tar:xz
+USE_CSTD=	c99
 PATHFIX_MAKEFILEIN=	Makefile.pre.in
 USE_LDCONFIG=	yes
 GNU_CONFIGURE=	yes