diff --git a/lib/jekyll/liquid_renderer.rb b/lib/jekyll/liquid_renderer.rb
index d46c0cc2..55e4e0fb 100644
--- a/lib/jekyll/liquid_renderer.rb
+++ b/lib/jekyll/liquid_renderer.rb
@@ -7,8 +7,8 @@ module Jekyll
   class LiquidRenderer
     extend Forwardable
 
-    def_delegator :@site, :in_source_dir, :source_dir
-    def_delegator :@site, :in_theme_dir, :theme_dir
+    private def_delegator :@site, :in_source_dir, :source_dir
+    private def_delegator :@site, :in_theme_dir, :theme_dir
 
     def initialize(site)
       @site = site
@@ -24,7 +24,7 @@ module Jekyll
       filename.match(filename_regex)
       filename =
         if Regexp.last_match(1) == theme_dir("")
-          ::File.join(Regexp.last_match(1).split("/")[-1], Regexp.last_match(2))
+          ::File.join(::File.basename(Regexp.last_match(1)), Regexp.last_match(2))
         else
           Regexp.last_match(2)
         end
@@ -53,7 +53,7 @@ module Jekyll
     private
 
     def filename_regex
-      %r!\A(#{source_dir}/|#{theme_dir}/|\W*)(.*)!oi
+      @filename_regex ||= %r!\A(#{source_dir}/|#{theme_dir}/|\W*)(.*)!i
     end
 
     def new_profile_hash