diff --git a/README.md b/README.md
index 08f5f29..a0ab82f 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ string.
 To use alertmanager2es, you'll need:
 
 - an [Elasticsearch][] cluster
-- [Alertmanager][]
+- [Alertmanager][] 0.6.0 or above
 
 To build alertmanager2es, you'll need: