diff --git a/version.h b/version.h
index d0094f4017..d4a6c134fe 100644
--- a/version.h
+++ b/version.h
@@ -4,7 +4,7 @@
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 12
-#define RUBY_RELEASE_DAY 20
+#define RUBY_RELEASE_DAY 21
 
 #include "ruby/version.h"