diff --git a/gitlab/objects.py b/gitlab/objects.py
index 99cf923e4..7c961b380 100644
--- a/gitlab/objects.py
+++ b/gitlab/objects.py
@@ -1728,7 +1728,7 @@ class ProjectMergeRequest(GitlabObject):
     requiredUrlAttrs = ['project_id']
     requiredCreateAttrs = ['source_branch', 'target_branch', 'title']
     optionalCreateAttrs = ['assignee_id', 'description', 'target_project_id',
-                           'labels', 'milestone_id']
+                           'labels', 'milestone_id', 'remove_source_branch']
     optionalUpdateAttrs = ['target_branch', 'assignee_id', 'title',
                            'description', 'state_event', 'labels',
                            'milestone_id']