diff --git a/js/moz-parser.js b/js/moz-parser.js
index ca6d6f9b..7d8151bc 100644
--- a/js/moz-parser.js
+++ b/js/moz-parser.js
@@ -7,19 +7,6 @@ var mozParser = (() => {
   const propertyToCss = {urls: 'url', urlPrefixes: 'url-prefix', domains: 'domain', regexps: 'regexp'};
   const CssToProperty = {'url': 'urls', 'url-prefix': 'urlPrefixes', 'domain': 'domains', 'regexp': 'regexps'};
 
-  function backtrackTo(parser, tokenType, startEnd) {
-    const tokens = parser._tokenStream._lt;
-    for (let i = parser._tokenStream._ltIndex - 1; i >= 0; --i) {
-      if (tokens[i].type === tokenType) {
-        return {line: tokens[i][startEnd + 'Line'], col: tokens[i][startEnd + 'Col']};
-      }
-    }
-  }
-
-  function trimNewLines(s) {
-    return s.replace(/^[\s\n]+/, '').replace(/[\s\n]+$/, '');
-  }
-
   function parseMozFormat(mozStyle) {
     return new Promise((resolve, reject) => {
       const parser = new parserlib.css.Parser();
@@ -28,15 +15,21 @@ var mozParser = (() => {
       const errors = [];
       const sections = [];
 
-      parser.addListener('startdocument', function (e) {
+      parser.addListener('startdocument', e => {
         const lastSection = sectionStack[sectionStack.length - 1];
-        let outerText = getRange(lastSection.start, (--e.col, e));
+        let outerText = getRange(lastSection.start, {line: e.line, col: e.col - 1});
         const gapComment = outerText.match(/(\/\*[\s\S]*?\*\/)[\s\n]*$/);
-        const section = {code: '', start: backtrackTo(this, parserlib.css.Tokens.LBRACE, 'end')};
+        const section = {
+          code: '',
+          start: {
+            line: parser._tokenStream._token.endLine,
+            col: parser._tokenStream._token.endCol,
+          },
+        };
         // move last comment before @-moz-document inside the section
         if (gapComment && !gapComment[1].match(/\/\*\s*AGENT_SHEET\s*\*\//)) {
           section.code = gapComment[1] + '\n';
-          outerText = trimNewLines(outerText.substring(0, gapComment.index));
+          outerText = outerText.substring(0, gapComment.index).trim();
         }
         if (outerText.trim()) {
           lastSection.code = outerText;