diff --git a/django/applications/catmaid/control/skeletonexport.py b/django/applications/catmaid/control/skeletonexport.py
index 2fde21fdc5..d6a99b6dcb 100644
--- a/django/applications/catmaid/control/skeletonexport.py
+++ b/django/applications/catmaid/control/skeletonexport.py
@@ -665,7 +665,7 @@ def _compact_skeleton(project_id, skeleton_id, with_connectors=True,
     if with_connectors or with_tags or with_annotations:
         # postgres is caching this query
         cursor.execute("""
-                SELECT relation_name, id FROM relation WHERE project_id={project_id}
+                SELECT relation_name, id FROM relation WHERE project_id=%(project_id)s
             """, {
                 'project_id': project_id,
             })