diff --git a/usr.bin/diff/Makefile b/usr.bin/diff/Makefile
index a9f79d3d81e1..4879570306ba 100644
--- a/usr.bin/diff/Makefile
+++ b/usr.bin/diff/Makefile
@@ -1,11 +1,12 @@
 # $FreeBSD$
 
 .include <src.opts.mk>
 
 PROG=	diff
 SRCS=	diff.c diffdir.c diffreg.c xmalloc.c pr.c
+LIBADD=	m
 
 HAS_TESTS=
 SUBDIR.${MK_TESTS}+= tests
 
 .include <bsd.prog.mk>