1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index caef68c769..42528c0fd5 100644
--- a/io.c
+++ b/io.c
@@ -7543,7 +7543,7 @@ rb_output_fs_setter(VALUE val, ID id, VALUE *var)
 {
     rb_str_setter(val, id, &val);
     if (!NIL_P(val)) {
-        rb_warn("non-nil $, will be deprecated");
+        rb_warn_deprecated("`$,'", NULL);
     }
     *var = val;
 }