diff --git a/lib/nylas/resources/auth.rb b/lib/nylas/resources/auth.rb
index 4133d5a8..6c30c066 100644
--- a/lib/nylas/resources/auth.rb
+++ b/lib/nylas/resources/auth.rb
@@ -151,7 +151,7 @@ def build_query_with_pkce(config, secret_hash)
     def url_auth_builder(config)
       builder = URI.parse(api_uri)
       builder.path = "/v3/connect/auth"
-      builder.query = URI.encode_www_form(build_query(config)).gsub!("+", "%20")
+      builder.query = URI.encode_www_form(build_query(config)).gsub(/\+/, "%20")
 
       builder
     end