diff --git a/include/types/server.h b/include/types/server.h
index 87ca0be..ac7ab7b 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -60,6 +60,7 @@
 #define SRV_TPROXY_MASK	0x0700	/* bind to a non-local address to reach this server */
 #define SRV_SEND_PROXY	0x0800	/* this server talks the PROXY protocol */
 #define SRV_NON_STICK	0x1000	/* never add connections allocated to this server to a stick table */
+#define SRV_CHK_RUNNING 0x2000  /* a check is currently running on this server */
 
 /* function which act on servers need to return various errors */
 #define SRV_STATUS_OK       0   /* everything is OK. */