diff --git a/fastlane/lib/fastlane/setup/setup.rb b/fastlane/lib/fastlane/setup/setup.rb
index dd6f4e5c238..6ed46b9a01b 100644
--- a/fastlane/lib/fastlane/setup/setup.rb
+++ b/fastlane/lib/fastlane/setup/setup.rb
@@ -244,7 +244,7 @@ def setup_gemfile!
 
     def ensure_gemfile_valid!(update_gemfile_if_needed: false)
       gemfile_content = File.read(gemfile_path)
-      unless gemfile_content.include?("https://rubygems.org")
+      unless gemfile_content.lines.any? { |line| URI(line.strip).host == "rubygems.org" rescue false }
         UI.error("You have a local Gemfile, but RubyGems isn't defined as source")
         UI.error("Please update your Gemfile at path `#{gemfile_path}` to include")
         UI.important("")