diff --git a/usr.bin/truss/syscalls.c b/usr.bin/truss/syscalls.c
index 9ee8bb102009..59b8cf293743 100644
--- a/usr.bin/truss/syscalls.c
+++ b/usr.bin/truss/syscalls.c
@@ -141,8 +141,10 @@ static struct syscall syscalls[] = {
 	  .args = { { Name, 0 } } },
 	{ .name = "chroot", .ret_type = 0, .nargs = 1,
 	  .args = { { Name, 0 } } },
+	{ .name = "mkfifo", .ret_type = 0, .nargs = 2,
+	  .args = { { Name, 0 }, { Octal, 1 } } },
 	{ .name = "mknod", .ret_type = 0, .nargs = 3,
-	  .args = { { Name, 0 }, { Octal, 1 }, { Int, 3 } } },
+	  .args = { { Name, 0 }, { Octal, 1 }, { Int, 2 } } },
 	{ .name = "chmod", .ret_type = 0, .nargs = 2,
 	  .args = { { Name, 0 }, { Octal, 1 } } },
 	{ .name = "chown", .ret_type = 0, .nargs = 3,