diff --git a/usr.bin/less/Makefile b/usr.bin/less/Makefile
index ca9d948e1e4..c55ce3581cb 100644
--- a/usr.bin/less/Makefile
+++ b/usr.bin/less/Makefile
@@ -19,7 +19,7 @@ LINKS=	${BINDIR}/less ${BINDIR}/more \
 MLINKS=	less.1 more.1
 CLEANFILES= less.1
 
-CFLAGS+=	${NO_WDEPRECATED_NON_PROTOTYPE}
-
 .include "Makefile.common"
 .include <bsd.prog.mk>
+
+CWARNFLAGS+=	${NO_WDEPRECATED_NON_PROTOTYPE}
diff --git a/usr.bin/lessecho/Makefile b/usr.bin/lessecho/Makefile
index af0a7c1550a..0d40cc20954 100644
--- a/usr.bin/lessecho/Makefile
+++ b/usr.bin/lessecho/Makefile
@@ -6,3 +6,5 @@ CLEANFILES= lessecho.1
 
 .include "${SRCTOP}/usr.bin/less/Makefile.common"
 .include <bsd.prog.mk>
+
+CWARNFLAGS+=	${NO_WDEPRECATED_NON_PROTOTYPE}
diff --git a/usr.bin/lesskey/Makefile b/usr.bin/lesskey/Makefile
index 4677e7c7e6c..6809d9dba12 100644
--- a/usr.bin/lesskey/Makefile
+++ b/usr.bin/lesskey/Makefile
@@ -6,3 +6,5 @@ CLEANFILES= lesskey.1
 
 .include "${SRCTOP}/usr.bin/less/Makefile.common"
 .include <bsd.prog.mk>
+
+CWARNFLAGS+=	${NO_WDEPRECATED_NON_PROTOTYPE}