diff --git a/usr.bin/false/false.c b/usr.bin/false/false.c
index 11d69ae68657..da950f9c180d 100644
--- a/usr.bin/false/false.c
+++ b/usr.bin/false/false.c
@@ -44,7 +44,7 @@ static const char sccsid[] = "@(#)false.c	8.1 (Berkeley) 6/6/93";
 #endif /* not lint */
 
 int
-main()
+main(void)
 {
 	return 1;
 }
diff --git a/usr.bin/true/true.c b/usr.bin/true/true.c
index ac17b6cce8a0..8e2f2554396a 100644
--- a/usr.bin/true/true.c
+++ b/usr.bin/true/true.c
@@ -44,7 +44,7 @@ static const char sccsid[] = "@(#)true.c	8.1 (Berkeley) 6/9/93";
 #endif /* not lint */
 
 int
-main()
+main(void)
 {
 	return 0;
 }