diff --git a/lib/liquid/standardfilters.rb b/lib/liquid/standardfilters.rb
index 0c738f73..1ddd800a 100644
--- a/lib/liquid/standardfilters.rb
+++ b/lib/liquid/standardfilters.rb
@@ -305,7 +305,7 @@ module Liquid
 
       def initialize(input)
         @input =
-          if input.is_a?(Array) || input.kind_of?(Enumerable)
+          if input.kind_of?(Enumerable)
             input
           else
             Array(input)