diff --git a/src/analyzer.js b/src/analyzer.js
index 40372749..c58d5e93 100644
--- a/src/analyzer.js
+++ b/src/analyzer.js
@@ -20,7 +20,8 @@ module.exports = {
 function getViewerData(bundleStats, bundleDir, opts) {
   const {
     logger = new Logger(),
-    excludeAssets = null
+    excludeAssets = null,
+    compressedSize = gzipSize
   } = opts || {};
 
   const isAssetIncluded = createAssetsFilter(excludeAssets);
@@ -102,7 +103,7 @@ function getViewerData(bundleStats, bundleDir, opts) {
 
     if (assetSources) {
       asset.parsedSize = Buffer.byteLength(assetSources.src);
-      asset.gzipSize = gzipSize(assetSources.src);
+      asset.gzipSize = compressedSize(assetSources.src);
     }
 
     // Picking modules from current bundle script
@@ -143,7 +144,7 @@ function getViewerData(bundleStats, bundleDir, opts) {
     }
 
     asset.modules = assetModules;
-    asset.tree = createModulesTree(asset.modules);
+    asset.tree = createModulesTree(asset.modules, {compressedSize});
     return result;
   }, {});
 
@@ -203,8 +204,8 @@ function isRuntimeModule(statModule) {
   return statModule.moduleType === 'runtime';
 }
 
-function createModulesTree(modules) {
-  const root = new Folder('.');
+function createModulesTree(modules, opts) {
+  const root = new Folder('.', opts);
 
   modules.forEach(module => root.addModule(module));
   root.mergeNestedFolders();
diff --git a/src/tree/Folder.js b/src/tree/Folder.js
index fb121be6..15748227 100644
--- a/src/tree/Folder.js
+++ b/src/tree/Folder.js
@@ -1,5 +1,4 @@
 import _ from 'lodash';
-import {gzipSize} from '../sizeUtils';
 
 import Module from './Module';
 import BaseFolder from './BaseFolder';
@@ -8,13 +7,18 @@ import {getModulePathParts} from './utils';
 
 export default class Folder extends BaseFolder {
 
+  constructor(name, opts) {
+    super(name);
+    this.opts = opts;
+  }
+
   get parsedSize() {
     return this.src ? this.src.length : 0;
   }
 
   get gzipSize() {
     if (!_.has(this, '_gzipSize')) {
-      this._gzipSize = this.src ? gzipSize(this.src) : 0;
+      this._gzipSize = this.src ? this.opts.compressedSize(this.src) : 0;
     }
 
     return this._gzipSize;
@@ -42,7 +46,7 @@ export default class Folder extends BaseFolder {
         // See `test/stats/with-invalid-dynamic-require.json` as an example.
         !(childNode instanceof Folder)
       ) {
-        childNode = currentFolder.addChildFolder(new Folder(folderName));
+        childNode = currentFolder.addChildFolder(new Folder(folderName, this.opts));
       }
 
       currentFolder = childNode;