diff --git a/usr.bin/less/Makefile b/usr.bin/less/Makefile
--- a/usr.bin/less/Makefile
+++ b/usr.bin/less/Makefile
@@ -19,7 +19,7 @@
 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
--- a/usr.bin/lessecho/Makefile
+++ b/usr.bin/lessecho/Makefile
@@ -6,3 +6,5 @@
 
 .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
--- a/usr.bin/lesskey/Makefile
+++ b/usr.bin/lesskey/Makefile
@@ -6,3 +6,5 @@
 
 .include "${SRCTOP}/usr.bin/less/Makefile.common"
 .include <bsd.prog.mk>
+
+CWARNFLAGS+=	${NO_WDEPRECATED_NON_PROTOTYPE}