diff --git a/Python/ast_unparse.c b/Python/ast_unparse.c
index ae623e0b4171f8..557c12cfda61ff 100644
--- a/Python/ast_unparse.c
+++ b/Python/ast_unparse.c
@@ -749,6 +749,7 @@ append_templatestr(PyUnicodeWriter *writer, expr_ty e)
             goto error;
         }
     }
+    _PyArena_Free(arena);
 
     return 0;