diff --git a/.hgtags b/.hgtags
index d95f8ddd0..eafe3d07e 100644
--- a/.hgtags
+++ b/.hgtags
@@ -68,3 +68,4 @@ b4a70b99171ade6e9628a87780994238950a1df1 ns-3.17
 cfbc9491d7e7c9d346cc042fd35b8afb8836e81f ns-3.18
 322102df792e2be6c74df74f776b3470fb1db795 ns-3.19
 da0eb48df23f96335f32a37f047a6bc27e197c8d ns-3.20
+fa4be182ef17746cea50e89af557c79a28b76533 ns-3.21