diff --git a/release_dashboard/utils/build.py b/release_dashboard/utils/build.py
index 6ee4b0c..db58662 100644
--- a/release_dashboard/utils/build.py
+++ b/release_dashboard/utils/build.py
@@ -14,6 +14,7 @@
 # with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import logging
+import string
 import uuid
 import urllib
 import requests
@@ -85,6 +86,11 @@ def trigger_build(project, trigger_release=None,
     if trigger_branch_or_tag.startswith("tag/"):
         tag = trigger_branch_or_tag.split("tag/")[1]
         params['tag'] = urllib.parse.quote(tag)
+
+        # branch is like tag but removing the last element,
+        # e.g. tag=mr5.5.2.1 -> branch=mr5.5.2
+        branch = string.join(tag.split(".")[0:-1], ".")
+        params['branch'] = urllib.parse.quote(branch)
     elif trigger_branch_or_tag.startswith("branch/"):
         branch = trigger_branch_or_tag.split("branch/")[1]
         params['branch'] = urllib.parse.quote(branch)