diff --git a/lib/rack_timer/stack.rb b/lib/rack_timer/stack.rb
index 72f42e2..f34c64b 100644
--- a/lib/rack_timer/stack.rb
+++ b/lib/rack_timer/stack.rb
@@ -1,5 +1,5 @@
 module ActionDispatch
-  class MiddlewareStack < Array
+  class MiddlewareStack
 
     # this class will wrap around each Rack-based middleware and take timing snapshots of how long
     # each middleware takes to execute
@@ -70,7 +70,7 @@ def build(app)
     def build(app = nil, &block)
       app ||= block
       raise "MiddlewareStack#build requires an app" unless app
-      reverse.inject(RackTimer.new(app)) { |a, e| e.build(a) }
+      to_a.reverse.inject(RackTimer.new(app)) { |a, e| e.build(a) }
     end
 
   end