diff --git a/.hgtags b/.hgtags
index cac5436c60d5..5b37bcb064af 100644
--- a/.hgtags
+++ b/.hgtags
@@ -182,3 +182,4 @@ f53ecf8eee2a0d2a7705d7ea3ec8682028e922a0 FIREFOX_NIGHTLY_74_END
 200615cdc7c34a7fdfb2f7ffba158dae2cbf49d5 FIREFOX_BETA_77_BASE
 5b8406a0446906d7228e5d745549b50a3496dc0f FIREFOX_NIGHTLY_77_END
 e4b11f027efc1f8c2710ae3f52487a8f10a8fb39 FIREFOX_BETA_78_BASE
+702ad0fa15860f6ea37effdcb45973cc63d3125b FIREFOX_NIGHTLY_78_END