diff --git a/zerver/webhooks/gitlab/tests.py b/zerver/webhooks/gitlab/tests.py
index ebd246ca2c..34032f2be4 100644
--- a/zerver/webhooks/gitlab/tests.py
+++ b/zerver/webhooks/gitlab/tests.py
@@ -369,7 +369,7 @@ A trivial change that should probably be ignored.
 
     def test_merge_request_updated_event_message(self) -> None:
         expected_topic = "my-awesome-project / MR #3 New Merge Request"
-        expected_message = "Tomasz Kolek updated [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3) (assigned to Tomasz Kolek) from `tomek` to `master`:\n\n~~~ quote\nupdated desc\n~~~"
+        expected_message = "Tomasz Kolek updated [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3) (assigned to Tomasz Kolek):\n\n~~~ quote\nupdated desc\n~~~"
         self.check_webhook(
             "merge_request_hook__merge_request_updated", expected_topic, expected_message
         )
@@ -383,7 +383,7 @@ A trivial change that should probably be ignored.
 
     def test_merge_request_merged_event_message(self) -> None:
         expected_topic = "my-awesome-project / MR #3 New Merge Request"
-        expected_message = "Tomasz Kolek merged [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3)."
+        expected_message = "Tomasz Kolek merged [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3) from `tomek` to `master`."
 
         self.check_webhook(
             "merge_request_hook__merge_request_merged", expected_topic, expected_message
@@ -589,7 +589,7 @@ A trivial change that should probably be ignored.
 
     def test_system_merge_request_merged_event_message(self) -> None:
         expected_topic = "my-awesome-project / MR #3 New Merge Request"
-        expected_message = "Tomasz Kolek merged [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3)."
+        expected_message = "Tomasz Kolek merged [MR #3](https://gitlab.com/tomaszkolek0/my-awesome-project/merge_requests/3) from `tomek` to `master`."
 
         self.check_webhook("system_hook__merge_request_merged", expected_topic, expected_message)
 
diff --git a/zerver/webhooks/gitlab/view.py b/zerver/webhooks/gitlab/view.py
index d961b89b2d..96984f84e1 100644
--- a/zerver/webhooks/gitlab/view.py
+++ b/zerver/webhooks/gitlab/view.py
@@ -132,11 +132,19 @@ def get_merge_request_updated_event_body(payload: WildValue, include_title: bool
 
 def get_merge_request_event_body(payload: WildValue, action: str, include_title: bool) -> str:
     pull_request = payload["object_attributes"]
+    target_branch = None
+    base_branch = None
+    if action == "merged":
+        target_branch = pull_request["source_branch"].tame(check_string)
+        base_branch = pull_request["target_branch"].tame(check_string)
+
     return get_pull_request_event_message(
         get_issue_user_name(payload),
         action,
         pull_request["url"].tame(check_string),
         pull_request["iid"].tame(check_int),
+        target_branch=target_branch,
+        base_branch=base_branch,
         type="MR",
         title=payload["object_attributes"]["title"].tame(check_string) if include_title else None,
     )
@@ -151,8 +159,8 @@ def get_merge_request_open_or_updated_body(
         action,
         pull_request["url"].tame(check_string),
         pull_request["iid"].tame(check_int),
-        pull_request["source_branch"].tame(check_string),
-        pull_request["target_branch"].tame(check_string),
+        pull_request["source_branch"].tame(check_string) if action == "created" else None,
+        pull_request["target_branch"].tame(check_string) if action == "created" else None,
         pull_request["description"].tame(check_string),
         assignees=replace_assignees_username_with_name(get_assignees(payload)),
         type="MR",