diff --git a/lib/bullet/detector/unused_eager_association.rb b/lib/bullet/detector/unused_eager_association.rb
index 26b656b9..2d0db37b 100644
--- a/lib/bullet/detector/unused_eager_association.rb
+++ b/lib/bullet/detector/unused_eager_association.rb
@@ -23,11 +23,13 @@ def self.create_notification(klazz, associations)
       end
 
       def self.call_object_association( object, association )
-        eager_loadings.similarly_associated( object, association ).
-                       collect { |related_object| call_object_associations[related_object] }.
-                       compact.
-                       flatten.
-                       uniq
+        all = Set.new
+        eager_loadings.similarly_associated( object, association ).each do |related_object|
+            coa = call_object_associations[related_object]
+            next if coa.nil?
+            all.merge coa
+        end
+        all.to_a
       end
 
       def self.diff_object_association( object, association )
diff --git a/lib/bullet/registry/base.rb b/lib/bullet/registry/base.rb
index 025a831a..2ad9fab3 100644
--- a/lib/bullet/registry/base.rb
+++ b/lib/bullet/registry/base.rb
@@ -24,19 +24,14 @@ def select( *args, &block )
       end
 
       def add( key, value )
-        @registry[key] ||= []
+        @registry[key] ||= Set.new
         if value.is_a? Array
           @registry[key] += value
         else
           @registry[key] << value
         end
-        unique( @registry[key] )
       end
 
-      private
-      def unique( array )
-        array.uniq!
-      end
     end
   end
 end