diff --git a/lib/libdisk/Makefile b/lib/libdisk/Makefile
index 762c904d9ac9..a9786341ff97 100644
--- a/lib/libdisk/Makefile
+++ b/lib/libdisk/Makefile
@@ -12,7 +12,7 @@ SRCS=	blocks.c ${_change} chunk.c create_chunk.c disk.c ${_open_disk} \
 	rules.c write_disk.c write_${MACHINE}_disk.c
 INCS=	libdisk.h
 
-WARNS=	2
+WARNS?=	2
 
 CFLAGS+=	-I${.CURDIR}/../../sys/geom
 
diff --git a/lib/libngatm/Makefile b/lib/libngatm/Makefile
index abb3373aad2b..5ce38a6cc60a 100644
--- a/lib/libngatm/Makefile
+++ b/lib/libngatm/Makefile
@@ -5,7 +5,7 @@
 LIB=	ngatm
 SHLIB_MAJOR= 1
 MAN=	libngatm.3 uniaddr.3 unifunc.3 unimsg.3 unistruct.3
-WARNS=	6
+WARNS?=	6
 
 # source of the library lives in contrib
 SDIR=	${.CURDIR}/../../sys