diff --git a/spec/bundler/support/path.rb b/spec/bundler/support/path.rb
index 8010b2f293..b26e77d376 100644
--- a/spec/bundler/support/path.rb
+++ b/spec/bundler/support/path.rb
@@ -102,7 +102,18 @@ module Spec
     end
 
     def tmp(*path)
-      source_root.join("tmp", scope, *path)
+      tmp_root(scope).join(*path)
+    end
+
+    def tmp_root(scope)
+      source_root.join("tmp", "#{test_env_version}.#{scope}")
+    end
+
+    # Bump this version whenever you make a breaking change to the spec setup
+    # that requires regenerating tmp/.
+
+    def test_env_version
+      1
     end
 
     def scope
diff --git a/spec/bundler/support/rubygems_ext.rb b/spec/bundler/support/rubygems_ext.rb
index fb03d4892e..fb76e34a74 100644
--- a/spec/bundler/support/rubygems_ext.rb
+++ b/spec/bundler/support/rubygems_ext.rb
@@ -57,8 +57,8 @@ module Spec
       install_test_deps
 
       (2..Parallel.processor_count).each do |n|
-        source = Path.source_root.join("tmp", "1")
-        destination = Path.source_root.join("tmp", n.to_s)
+        source = Path.tmp_root("1")
+        destination = Path.tmp_root(n.to_s)
 
         FileUtils.rm_rf destination
         FileUtils.cp_r source, destination