diff --git a/amaranth/vendor/_gowin.py b/amaranth/vendor/_gowin.py
index a85043b18..e2f53d9b0 100644
--- a/amaranth/vendor/_gowin.py
+++ b/amaranth/vendor/_gowin.py
@@ -352,7 +352,7 @@ def _osc_div(self):
                     IO_PORT "{{port_name}}" {{attr_name}}={{attr_value}};
                 {% endfor %}
             {% endfor %}
-            {{get_override("add_preferences")|default("# (add_preferences placeholder)")}}
+            {{get_override("add_preferences")|default("// (add_preferences placeholder)")}}
         """,
     }