diff --git a/include/haproxy/server-t.h b/include/haproxy/server-t.h
index a01081d54..e190f9053 100644
--- a/include/haproxy/server-t.h
+++ b/include/haproxy/server-t.h
@@ -150,6 +150,7 @@ enum srv_initaddr {
 #define SRV_F_SOCKS4_PROXY 0x0400        /* this server uses SOCKS4 proxy */
 #define SRV_F_NO_RESOLUTION 0x0800       /* disable runtime DNS resolution on this server */
 #define SRV_F_DYNAMIC      0x1000        /* dynamic server instantiated at runtime */
+#define SRV_F_NON_PURGEABLE 0x2000       /* this server cannot be removed at runtime */
 
 /* configured server options for send-proxy (server->pp_opts) */
 #define SRV_PP_V1               0x0001   /* proxy protocol version 1 */