diff --git a/lib/liquid/standardfilters.rb b/lib/liquid/standardfilters.rb
index aa0a3821..bd2a128f 100644
--- a/lib/liquid/standardfilters.rb
+++ b/lib/liquid/standardfilters.rb
@@ -308,12 +308,12 @@ module Liquid
 
     # remove the first occurrences of a substring
     def remove_first(input, string)
-      replace_first(input.to_s, string, '')
+      replace_first(input, string, '')
     end
 
     # remove the last occurences of a substring
     def remove_last(input, string)
-      replace_last(input.to_s, string, '')
+      replace_last(input, string, '')
     end
 
     # add one string to another