--- a/testing/mozharness/scripts/release/postrelease_version_bump.py
+++ b/testing/mozharness/scripts/release/postrelease_version_bump.py
@@ -166,15 +166,19 @@ class PostReleaseVersionBump(MercurialSc
     def tag(self):
         dirs = self.query_abs_dirs()
         tags = ["{product}_{version}_BUILD{build_number}",
                 "{product}_{version}_RELEASE"]
         tags = [t.format(product=self.config["product"].upper(),
                          version=self.config["version"].replace(".", "_"),
                          build_number=self.config["build_number"])
                 for t in tags]
+        message = "No bug - Tagging {revision} with {tags} a=release CLOSED TREE"
+        message = message.format(
+            revision=self.config["revision"],
+            tags=', '.join(tags))
         self.hg_tag(cwd=dirs["abs_gecko_dir"], tags=tags,
-                    revision=self.config["revision"],
+                    revision=self.config["revision"], message=message,
                     user=self.config["hg_user"], force=True)
 
 # __main__ {{{1
 if __name__ == '__main__':
     PostReleaseVersionBump().run_and_exit()