1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index 9f1550812a..2404b1faf5 100644
--- a/io.c
+++ b/io.c
@@ -1083,7 +1083,7 @@ rb_io_ungetc(io, c)
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
 
-    if (ungetc(cc, fptr->f) == EOF)
+    if (ungetc(cc, fptr->f) == EOF && cc != EOF)
 	rb_sys_fail(fptr->path);
     return Qnil;
 }