diff --git a/psycopg/lobject_int.c b/psycopg/lobject_int.c
index 2f78e90b..43f2b179 100644
--- a/psycopg/lobject_int.c
+++ b/psycopg/lobject_int.c
@@ -253,7 +253,7 @@ lobject_close_locked(lobjectObject *self, char **error)
         return 0;
         break;
     default:
-        PyErr_SetString(OperationalError, "the connection is broken");
+        *error = strdup("the connection is broken");
         return -1;
         break;
     }