diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
index 72e77249cc..4d5fa7e0d2 100644
--- a/Library/Homebrew/requirement.rb
+++ b/Library/Homebrew/requirement.rb
@@ -239,7 +239,13 @@ class Requirement
         end
       end
 
-      cache[cache_key][cache_id dependent] = reqs.dup if cache_key.present?
+      if cache_key.present?
+        # Even though we setup the cache above
+        # 'dependent.recursive_dependencies.map(&:to_formula)'
+        # is invalidating the singleton cache
+        cache[cache_key] ||= {}
+        cache[cache_key][cache_id dependent] = reqs.dup
+      end
       reqs
     end