diff --git a/Library/Homebrew/dev-cmd/test-bot.rb b/Library/Homebrew/dev-cmd/test-bot.rb
index 9bb7162f97..c70e83b899 100644
--- a/Library/Homebrew/dev-cmd/test-bot.rb
+++ b/Library/Homebrew/dev-cmd/test-bot.rb
@@ -354,7 +354,7 @@ module Homebrew
       elsif @url
         # TODO: in future Travis CI may need to also use `brew pull` to e.g. push
         # the right commit to BrewTestBot.
-        if !travis_pr || ENV["ghprbActualCommit"].chomp != `git rev-parse HEAD`
+        if !travis_pr || `git rev-parse #{ENV["sha1"]}` != `git rev-parse HEAD`
           diff_start_sha1 = current_sha1
           test "brew", "pull", "--clean", @url
           diff_end_sha1 = current_sha1