diff --git a/source/javascripts/app/_toc.js b/source/javascripts/app/_toc.js
index eb20fef..6bb3bc9 100644
--- a/source/javascripts/app/_toc.js
+++ b/source/javascripts/app/_toc.js
@@ -38,7 +38,7 @@
       $toc.find(tocLinkSelector).each(function() {
         var targetId = $(this).attr('href');
         if (targetId[0] === "#") {
-          headerHeights[targetId] = $(targetId).offset().top;
+          headerHeights[targetId] = $("#" + $.escapeSelector(targetId.substring(1))).offset().top;
         }
       });
     };