diff --git a/swh/web/assets/config/webpack-plugins/generate-weblabels-webpack-plugin/index.js b/swh/web/assets/config/webpack-plugins/generate-weblabels-webpack-plugin/index.js
--- a/swh/web/assets/config/webpack-plugins/generate-weblabels-webpack-plugin/index.js
+++ b/swh/web/assets/config/webpack-plugins/generate-weblabels-webpack-plugin/index.js
@@ -31,6 +31,7 @@
     // source file extension handled by webpack and compiled to js
     this.srcExts = ['js', 'ts', 'coffee', 'lua'];
     this.srcExtsRegexp = new RegExp('^.*.(' + this.srcExts.join('|') + ')$');
+    this.chunkIdToName = {};
     this.chunkNameToJsAsset = {};
     this.chunkJsAssetToSrcFiles = {};
     this.srcIdsInChunkJsAsset = {};
@@ -62,6 +63,12 @@
       this.weblabelsOutputDir = path.join(stats.outputPath, this.weblabelsDirName);
       this.recursiveMkdir(this.weblabelsOutputDir);
 
+      stats.assets.forEach(asset => {
+        for (let i = 0; i < asset.chunks.length; ++i) {
+          this.chunkIdToName[asset.chunks[i]] = asset.chunkNames[i];
+        }
+      });
+
       // map each generated webpack chunk to its js asset
       Object.keys(stats.assetsByChunkName).forEach((chunkName, i) => {
         if (Array.isArray(stats.assetsByChunkName[chunkName])) {
@@ -108,8 +115,8 @@
 
         // iterate on all chunks containing the module
         mod.chunks.forEach(chunk => {
-
-          let chunkJsAsset = stats.publicPath + this.chunkNameToJsAsset[chunk];
+          let chunkName = this.chunkIdToName[chunk];
+          let chunkJsAsset = stats.publicPath + this.chunkNameToJsAsset[chunkName];
 
           // init the chunk to source files mapping if needed
           if (!this.chunkJsAssetToSrcFiles.hasOwnProperty(chunkJsAsset)) {