diff --git a/ext/date/lib/timelib.h b/ext/date/lib/timelib.h
index c79fa9a4699..48a952e7901 100644
--- a/ext/date/lib/timelib.h
+++ b/ext/date/lib/timelib.h
@@ -26,6 +26,8 @@
 #include <limits.h>
 #endif
 
+#define TIMELIB_VERSION 201101
+
 #define TIMELIB_NONE             0x00
 #define TIMELIB_OVERRIDE_TIME    0x01
 #define TIMELIB_NO_CLONE         0x02