diff --git a/sources/lib/platform/linux/check_linux_es_status.sh b/sources/lib/platform/linux/check_linux_es_status.sh
index f17293e..8514954 100644
--- a/sources/lib/platform/linux/check_linux_es_status.sh
+++ b/sources/lib/platform/linux/check_linux_es_status.sh
@@ -127,10 +127,14 @@ case "${_ES_STATUS}" in
         _MSG="state of ES instance at ${_ES_URL} is OK [${_ES_STATUS}]"
         _STC=0
         ;;
-    *)
+    yellow|red)
         _MSG="state of ES instance at ${_ES_URL} is NOK [${_ES_STATUS}]"
         _STC=1
         ;;
+    *)
+        _MSG="state of ES instance at ${_ES_URL} is NOK [unknown]"
+        _STC=1
+        ;;
 esac
 if (( _LOG_HEALTHY > 0 || _STC > 0 ))
 then