diff --git a/wagtail/wagtailsearch/backends/elasticsearch.py b/wagtail/wagtailsearch/backends/elasticsearch.py
index 8499d4971..08e75f5aa 100644
--- a/wagtail/wagtailsearch/backends/elasticsearch.py
+++ b/wagtail/wagtailsearch/backends/elasticsearch.py
@@ -511,7 +511,7 @@ class ElasticsearchIndex(object):
         return self.es.indices.exists(self.name)
 
     def is_alias(self):
-        return self.es.indices.exists_alias(self.name)
+        return self.es.indices.exists_alias(name=self.name)
 
     def aliased_indices(self):
         """