diff --git a/include/net/netns/generic.h b/include/net/netns/generic.h
index 7ce68183f6e18..00c399edeed11 100644
--- a/include/net/netns/generic.h
+++ b/include/net/netns/generic.h
@@ -33,7 +33,7 @@ struct net_generic {
 			struct rcu_head rcu;
 		} s;
 
-		void *ptr[0];
+		DECLARE_FLEX_ARRAY(void *, ptr);
 	};
 };