diff --git a/Library/Homebrew/dev-cmd/pr-pull.rb b/Library/Homebrew/dev-cmd/pr-pull.rb
index 3effc9eaa211f2dd16cf87100995971c41c9014e..c849f4a94b05b2340418e7231ad97d53ac8c0273 100644
--- a/Library/Homebrew/dev-cmd/pr-pull.rb
+++ b/Library/Homebrew/dev-cmd/pr-pull.rb
@@ -104,9 +104,10 @@ module Homebrew
     if pr
       # This is a tap pull request and approving reviewers should also sign-off.
       tap = Tap.from_path(path)
-      trailers += GitHub.approved_reviews(tap.user, tap.full_name.split("/").last, pr).map do |r|
+      review_trailers = GitHub.approved_reviews(tap.user, tap.full_name.split("/").last, pr).map do |r|
         "Signed-off-by: #{r["name"]} <#{r["email"]}>"
-      end.join("\n")
+      end
+      trailers = trailers.lines.concat(review_trailers).map(&:strip).uniq.join("\n")
 
       # Append the close message as well, unless the commit body already includes it.
       close_message = "Closes ##{pr}."