diff --git a/lib/sumsub/request.rb b/lib/sumsub/request.rb
index cf48c88..c5e3e1e 100644
--- a/lib/sumsub/request.rb
+++ b/lib/sumsub/request.rb
@@ -218,7 +218,7 @@ def build_header(
         "X-App-Access-Ts": epoch_time.to_s.encode("UTF-8"),
         "Accept": accept,
         "Content-Type": content_type
-      }.compact!
+      }.compact
     end
 
     def parse_response(response)