diff --git a/lib/rails_admin/config/fields/types/file_upload.rb b/lib/rails_admin/config/fields/types/file_upload.rb
index b3ffe52e9a..1199c29041 100644
--- a/lib/rails_admin/config/fields/types/file_upload.rb
+++ b/lib/rails_admin/config/fields/types/file_upload.rb
@@ -52,7 +52,7 @@ class FileUpload < RailsAdmin::Config::Fields::Base
           end
 
           register_instance_option :image? do
-            mime_type = Mime::Type.lookup_by_extension(resource_url.to_s.split('.').last)
+            mime_type = Mime::Type.lookup_by_extension(resource_url.to_s.split('.').last&.split('?')&.first)
             mime_type.to_s.match?(/^image/)
           end