diff --git a/lib/link_thumbnailer/processor.rb b/lib/link_thumbnailer/processor.rb
index 9e57450..329e426 100644
--- a/lib/link_thumbnailer/processor.rb
+++ b/lib/link_thumbnailer/processor.rb
@@ -62,7 +62,7 @@ def perform_request
         response.body
       when ::Net::HTTPRedirection
         call(
-          resolve_relative_url(response['location']),
+          resolve_relative_url(response['location'].to_s),
           redirect_count + 1,
           headers
         )