diff --git a/include/types/proxy.h b/include/types/proxy.h
index ca24dbf..2518f88 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -487,7 +487,7 @@
 						 * name is used
 						 */
 	struct list filter_configs;		/* list of the filters that are declared on this proxy */
-	__decl_hathreads(HA_SPINLOCK_T lock);
+	__decl_hathreads(HA_SPINLOCK_T lock);   /* may be taken under the server's lock */
 };
 
 struct switching_rule {