diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index 228063d79b..0cc2f78787 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -11,7 +11,7 @@
 
 **********************************************************************/
 
-#define STRINGIO_VERSION "0.1.4"
+#define STRINGIO_VERSION "3.0.0"
 
 #include "ruby.h"
 #include "ruby/io.h"