diff --git a/app/helpers/blacklight/blacklight_helper_behavior.rb b/app/helpers/blacklight/blacklight_helper_behavior.rb
index b1c0778e..c4f1be07 100644
--- a/app/helpers/blacklight/blacklight_helper_behavior.rb
+++ b/app/helpers/blacklight/blacklight_helper_behavior.rb
@@ -331,7 +331,7 @@ def document_index_view_type(query_params = params)
     #
     # @param [String] format suffix
     # @yield
-    def with_format(format, _block)
+    def with_format(format, *, &block)
       old_formats = formats
       self.formats = [format]
       yield