diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index ed2b0a3fe8..4708a7c5c2 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -12,7 +12,7 @@
 
 **********************************************************************/
 
-#define STRINGIO_VERSION "3.0.3"
+#define STRINGIO_VERSION "3.0.4"
 
 #include "ruby.h"
 #include "ruby/io.h"