diff --git a/public/app/plugins/datasource/elasticsearch/partials/bucket_agg.html b/public/app/plugins/datasource/elasticsearch/partials/bucket_agg.html
index a180f97c994..d0cf23a3d93 100644
--- a/public/app/plugins/datasource/elasticsearch/partials/bucket_agg.html
+++ b/public/app/plugins/datasource/elasticsearch/partials/bucket_agg.html
@@ -101,6 +101,7 @@
 												get-options="getSizeOptions()"
 												on-change="onChangeInternal()"
 												label-mode="true"
+                        allow-custom="true"
 												css-class="width-12">
 			</gf-form-dropdown>
 		</div>