diff --git a/bundler/spec/spec_helper.rb b/bundler/spec/spec_helper.rb
index a79e33fbb016..0fbeb484f0ee 100644
--- a/bundler/spec/spec_helper.rb
+++ b/bundler/spec/spec_helper.rb
@@ -21,7 +21,7 @@
 
 # If we use shared GEM_HOME and install multiple versions, it may cause
 # unexpected test failures.
-gem "diff-lcs"
+gem "diff-lcs", "< 2.0"
 
 require "rspec/core"
 require "rspec/expectations"