diff --git a/spec/bundler/spec_helper.rb b/spec/bundler/spec_helper.rb
index 23db133b67..5f9ed0ec0a 100644
--- a/spec/bundler/spec_helper.rb
+++ b/spec/bundler/spec_helper.rb
@@ -78,10 +78,19 @@ RSpec.configure do |config|
     ENV["XDG_CONFIG_HOME"] = nil
     ENV["GEMRC"] = nil
 
+    extend(Spec::Helpers)
+
+    # Ruby-core needs RUBYLIB set, leave any "internal" RUBYLIB entries to avoid
+    # resetting that, but reset anything else to avoid external stuff like asdf
+    # hooks from interfering with our specs
+
+    rubylib = ENV["RUBYLIB"]
+    rubylib = rubylib.split(File::PATH_SEPARATOR).select {|p| p.start_with?(git_root.to_s) }.join(File::PATH_SEPARATOR) if rubylib
+    ENV["RUBYLIB"] = rubylib
+
     # Don't wrap output in tests
     ENV["THOR_COLUMNS"] = "10000"
 
-    extend(Spec::Helpers)
     system_gems :bundler, :path => pristine_system_gem_path
   end