diff --git a/.themes/classic/source/javascripts/octopress.js b/.themes/classic/source/javascripts/octopress.js
index 9e4f042..2bba4c0 100644
--- a/.themes/classic/source/javascripts/octopress.js
+++ b/.themes/classic/source/javascripts/octopress.js
@@ -40,17 +40,17 @@ function addSidebarToggler() {
 
 function addCodeLineNumbers() {
   if (navigator.appName === 'Microsoft Internet Explorer') { return; }
-  $('div.gist-highlight').each(function(code) {
+  $('div.gist-highlight').each(function(index) {
     var tableStart = '<table><tbody><tr><td class="gutter">',
         lineNumbers = '<pre class="line-numbers">',
         tableMiddle = '</pre></td><td class="code">',
         tableEnd = '</td></tr></tbody></table>',
-        count = $('.line', code).length;
+        count = $('.line', this).length;
     for (var i=1;i<=count; i++) {
       lineNumbers += '<span class="line-number">'+i+'</span>\n';
     }
-    var table = tableStart + lineNumbers + tableMiddle + '<pre>'+$('pre', code).html()+'</pre>' + tableEnd;
-    $(code).html(table);
+    var table = tableStart + lineNumbers + tableMiddle + '<pre>'+$('pre', this).html()+'</pre>' + tableEnd;
+    $(this).html(table);
   });
 }
 
diff --git a/plugins/backtick_code_block.rb b/plugins/backtick_code_block.rb
index c4581bf..8da510e 100644
--- a/plugins/backtick_code_block.rb
+++ b/plugins/backtick_code_block.rb
@@ -24,7 +24,7 @@ module BacktickCodeBlock
         if markup =~ AllOptions
           highlight(code, $1, {caption: $2, url: $3, anchor: $4 || 'Link', linenos: linenos, start: start, marks: marks})
         elsif markup =~ LangCaption
-          highlight(code, $1, {caption: $2 || '', linenos: linenos, start: start, marks: marks})
+          highlight(code, $1, {caption: $2 || nil, linenos: linenos, start: start, marks: marks})
         else
           highlight(code, 'plain', {linenos: linenos, start: start})
         end