diff --git a/theme/boost/templates/core/dataformat_selector.mustache b/theme/boost/templates/core/dataformat_selector.mustache
index 569bc369984..3e6fa78db4b 100644
--- a/theme/boost/templates/core/dataformat_selector.mustache
+++ b/theme/boost/templates/core/dataformat_selector.mustache
@@ -42,7 +42,7 @@
     <div class="form-inline text-xs-right">
         <input type="hidden" name="sesskey" value="{{sesskey}}">
         <label for="downloadtype_{{name}}" class="mr-1">{{label}}</label>
-        <select name="{{name}}" id="downloadtype_{{name}}" class="form-control">
+        <select name="{{name}}" id="downloadtype_{{name}}" class="form-control custom-select mr-1">
             {{#options}}
                 <option value="{{value}}">{{label}}</option>
             {{/options}}