diff --git a/usr.bin/yes/yes.c b/usr.bin/yes/yes.c
index 73716e23cd99..aae13b9a09b5 100644
--- a/usr.bin/yes/yes.c
+++ b/usr.bin/yes/yes.c
@@ -45,6 +45,7 @@ static const char rcsid[] = "$FreeBSD$";
 #endif
 #endif /* not lint */
 
+#include <err.h>
 #include <stdio.h>
 
 int