diff --git a/Gemfile b/Gemfile
index a5e73b39..6fbbfd43 100644
--- a/Gemfile
+++ b/Gemfile
@@ -26,7 +26,9 @@ group :test do
   gem "nokogiri", "~> 1.7"
   gem "rspec"
   gem "rspec-mocks"
-  gem "rubocop", "~> 0.65.0"
+  # Temporary lock on RuboCop version for Windows since Pysch-3.1.0 is not available
+  # for use on Ruby 2.6-mingw32 platforms
+  gem "rubocop", "~> 0.64.0" if Gem.win_platform?
   gem "test-dependency-theme", :path => File.expand_path("test/fixtures/test-dependency-theme", __dir__)
   gem "test-theme", :path => File.expand_path("test/fixtures/test-theme", __dir__)
   gem "test-theme-symlink", :path => File.expand_path("test/fixtures/test-theme-symlink", __dir__)