diff --git a/src/fileio.c b/src/fileio.c
index 606359a..e0226f8 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2981,7 +2981,7 @@
     int
 check_file_readonly(
     char_u	*fname,		/* full path to file */
-    int		perm)		/* known permissions on file */
+    int		perm UNUSED)	/* known permissions on file */
 {
 #ifndef USE_MCH_ACCESS
     int	    fd = 0;