diff --git a/src/kemal/static_file_handler.cr b/src/kemal/static_file_handler.cr
index ef592d0..dbeca28 100644
--- a/src/kemal/static_file_handler.cr
+++ b/src/kemal/static_file_handler.cr
@@ -75,5 +75,9 @@ module Kemal
         call_next(context)
       end
     end
+
+    private def modification_time(file_path)
+      File.info(file_path).modification_time
+    end
   end
 end