diff --git a/lib/eway_rapid/rapid_client.rb b/lib/eway_rapid/rapid_client.rb
index a5b34d3..51d99fb 100644
--- a/lib/eway_rapid/rapid_client.rb
+++ b/lib/eway_rapid/rapid_client.rb
@@ -298,7 +298,7 @@ def settlement_search(search_request)
     # @param [String] language The 2 letter code for the language to translate to (only en at this time)
     # @return [String] Error message
     def self.user_display_message(code, language = 'en')
-      find_error_code(code, language)
+      find_error_code(code, language.downcase)
     end
 
     # Gets the valid status of this Rapid client
diff --git a/test/eway_rapid/rapid_client_test.rb b/test/eway_rapid/rapid_client_test.rb
index 4d0e608..fdd6185 100644
--- a/test/eway_rapid/rapid_client_test.rb
+++ b/test/eway_rapid/rapid_client_test.rb
@@ -109,4 +109,10 @@ def test_find_error_code
     error_code = 'S9991'
     assert_equal('Library does not have PublicAPI key initialised, or Key is Invalid', EwayRapid::RapidClient.user_display_message(error_code))
   end
+
+  def test_find_error_code_with_langugage
+    error_code = 'S9991'
+    assert_equal('Library does not have PublicAPI key initialised, or Key is Invalid', EwayRapid::RapidClient.user_display_message(error_code, 'en'))
+    assert_equal('Library does not have PublicAPI key initialised, or Key is Invalid', EwayRapid::RapidClient.user_display_message(error_code, 'EN'))
+  end
 end
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