diff --git a/.hgtags b/.hgtags
index 4a3161fe0311..a07947733a8d 100644
--- a/.hgtags
+++ b/.hgtags
@@ -229,3 +229,4 @@ b81970e39db444fa9a70eaf2e656f3e48c18a7c1 FIREFOX_BETA_97_BASE
 c0ed4893120fe99dabf73c109dc77bdf109ae628 FIREFOX_NIGHTLY_98_END
 b20c5a948aaf5c9b8ca0819ff6d8ab83d0a0af8b FIREFOX_BETA_99_BASE
 923f64ad8d51a0ba1540c400bb6ee63cbe1233c4 FIREFOX_NIGHTLY_99_END
+8ab1c4f5058874d87bd1aefafbcc6a20b994f775 FIREFOX_BETA_100_BASE