diff --git a/.hgtags b/.hgtags
index 1223c8cae14e..563e2800266a 100644
--- a/.hgtags
+++ b/.hgtags
@@ -5083,3 +5083,4 @@ b5f945290d0a97227a9de2c841b6695e40a9f7c2 FIREFOX_128_1_0esr_RELEASE
 49e746f805bd2d0c6a18e9db2df6ccbac0242eae FIREFOX_128_2_0esr_RELEASE
 e2cb3d9c8cfc18acad7f77add351416dc95b67c4 FIREFOX_128_3_0esr_BUILD1
 e2cb3d9c8cfc18acad7f77add351416dc95b67c4 FIREFOX_128_3_0esr_RELEASE
+e0c969a3bfc0a23219384269e5b36a589c8f6cc5 FIREFOX_128_3_1esr_BUILD1