diff --git a/lib/parent-dummy-chains.js b/lib/parent-dummy-chains.js
index 59e95ab4..58a6a44a 100644
--- a/lib/parent-dummy-chains.js
+++ b/lib/parent-dummy-chains.js
@@ -1,17 +1,17 @@
 module.exports = parentDummyChains;
 
 function parentDummyChains(g) {
-  var postorderNums = postorder(g);
+  let postorderNums = postorder(g);
 
   g.graph().dummyChains.forEach(v => {
-    var node = g.node(v);
-    var edgeObj = node.edgeObj;
-    var pathData = findPath(g, postorderNums, edgeObj.v, edgeObj.w);
-    var path = pathData.path;
-    var lca = pathData.lca;
-    var pathIdx = 0;
-    var pathV = path[pathIdx];
-    var ascending = true;
+    let node = g.node(v);
+    let edgeObj = node.edgeObj;
+    let pathData = findPath(g, postorderNums, edgeObj.v, edgeObj.w);
+    let path = pathData.path;
+    let lca = pathData.lca;
+    let pathIdx = 0;
+    let pathV = path[pathIdx];
+    let ascending = true;
 
     while (v !== edgeObj.w) {
       node = g.node(v);
@@ -44,12 +44,12 @@ function parentDummyChains(g) {
 // Find a path from v to w through the lowest common ancestor (LCA). Return the
 // full path and the LCA.
 function findPath(g, postorderNums, v, w) {
-  var vPath = [];
-  var wPath = [];
-  var low = Math.min(postorderNums[v].low, postorderNums[w].low);
-  var lim = Math.max(postorderNums[v].lim, postorderNums[w].lim);
-  var parent;
-  var lca;
+  let vPath = [];
+  let wPath = [];
+  let low = Math.min(postorderNums[v].low, postorderNums[w].low);
+  let lim = Math.max(postorderNums[v].lim, postorderNums[w].lim);
+  let parent;
+  let lca;
 
   // Traverse up from v to find the LCA
   parent = v;
@@ -70,11 +70,11 @@ function findPath(g, postorderNums, v, w) {
 }
 
 function postorder(g) {
-  var result = {};
-  var lim = 0;
+  let result = {};
+  let lim = 0;
 
   function dfs(v) {
-    var low = lim;
+    let low = lim;
     g.children(v).forEach(dfs);
     result[v] = { low: low, lim: lim++ };
   }