diff --git a/capsul/database/populse_db.py b/capsul/database/populse_db.py
index fef69692..5ffba15e 100644
--- a/capsul/database/populse_db.py
+++ b/capsul/database/populse_db.py
@@ -83,7 +83,7 @@ def engine_id(self, label):
                     label=label, fields=["engine_id"], as_list=True
                 )
                 if s:
-                    return s[0]
+                    return s[0][0]
 
     def _enter(self):
         self.uuid = str(uuid4())