diff --git a/heartbeat/mysql b/heartbeat/mysql
index de56516..208c936 100755
--- a/heartbeat/mysql
+++ b/heartbeat/mysql
@@ -500,8 +500,7 @@ check_slave() {
 	    local master_pref
 	    master_pref=$((${OCF_RESKEY_max_slave_lag}-${secs_behind}))
 	    if [ $master_pref -lt 0 ]; then
-		# Sanitize a below-zero preference to just zero
-		master_pref=0
+		master_pref=-INFINITY
 	    fi
 	    $CRM_MASTER -v $master_pref
 	fi