diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index 2d0e5b3ffa..0ef2bb0141 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -61,6 +61,7 @@ module Homebrew
       ENV.delete("HOMEBREW_NO_GITHUB_API")
       ENV.delete("HOMEBREW_NO_EMOJI")
       ENV.delete("HOMEBREW_DEVELOPER")
+      ENV.delete("HOMEBREW_INSTALL_CLEANUP")
       ENV["HOMEBREW_NO_ANALYTICS_THIS_RUN"] = "1"
       ENV["HOMEBREW_NO_COMPAT"] = "1" if args.no_compat?
       ENV["HOMEBREW_TEST_GENERIC_OS"] = "1" if args.generic?