diff --git a/Library/Homebrew/upgrade.rb b/Library/Homebrew/upgrade.rb
index a64cabf5ac..b0d3c0f993 100644
--- a/Library/Homebrew/upgrade.rb
+++ b/Library/Homebrew/upgrade.rb
@@ -142,6 +142,7 @@ module Homebrew
 
       outdated_dependents =
         installed_formulae.flat_map(&:runtime_installed_formula_dependents)
+                          .uniq
                           .select(&:outdated?)
       return if outdated_dependents.blank? && already_broken_dependents.blank?