diff --git a/mrbgems/mruby-io/src/file_test.c b/mrbgems/mruby-io/src/file_test.c
index ec731b094..5d5ecb93f 100644
--- a/mrbgems/mruby-io/src/file_test.c
+++ b/mrbgems/mruby-io/src/file_test.c
@@ -1,5 +1,5 @@
 /*
-** file.c - File class
+** file_test.c - FileTest class
 */
 
 #include "mruby.h"