diff --git a/include/types/server.h b/include/types/server.h
index 6a7e558..130c370 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -86,6 +86,7 @@
 #define SRV_F_MAPPORTS     0x0002        /* this server uses mapped ports */
 #define SRV_F_NON_STICK    0x0004        /* never add connections allocated to this server to a stick table */
 #define SRV_F_USE_NS_FROM_PP 0x0008      /* use namespace associated with connection if present */
+#define SRV_F_FORCED_ID    0x0010        /* server's ID was forced in the configuration */
 
 /* configured server options for send-proxy (server->pp_opts) */
 #define SRV_PP_V1          0x0001        /* proxy protocol version 1 */
diff --git a/src/server.c b/src/server.c
index ee52903..9019674 100644
--- a/src/server.c
+++ b/src/server.c
@@ -161,6 +161,7 @@
 	}
 
 	eb32_insert(&curproxy->conf.used_server_id, &newsrv->conf.id);
+	newsrv->flags |= SRV_F_FORCED_ID;
 	return 0;
 }