diff --git a/lib/omniauth/strategies/slack.rb b/lib/omniauth/strategies/slack.rb
index 73befcb..3bba4c1 100644
--- a/lib/omniauth/strategies/slack.rb
+++ b/lib/omniauth/strategies/slack.rb
@@ -76,7 +76,7 @@ def team_identity
 
       def user_info
         url = URI.parse('/api/users.info')
-        url.query = Rack::Utils.build_query(user: user_identity['id'])
+        url.query = Rack::Utils.build_query(user: user_identity['id'] || access_token.params["user_id"])
         url = url.to_s
 
         @user_info ||= access_token.get(url).parsed