diff --git a/package-lock.json b/package-lock.json
index 5c017a1..c19c63a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -124,13 +124,13 @@
             "dev": true
         },
         "@types/terser-webpack-plugin": {
-            "version": "5.0.1",
-            "resolved": "https://registry.npmjs.org/@types/terser-webpack-plugin/-/terser-webpack-plugin-5.0.1.tgz",
-            "integrity": "sha512-kDxwsSDm5eVffzPpbu7uWSW2xVKmNAJ5YK6j7gdgww98rV+eGGhS9Wi0qNp0ZqCr923hI8JuSce2QO8pcdn3gQ==",
+            "version": "5.0.2",
+            "resolved": "https://registry.npmjs.org/@types/terser-webpack-plugin/-/terser-webpack-plugin-5.0.2.tgz",
+            "integrity": "sha512-YcAT1D4gjho1jqc/gjn1ojHFtQtrGHaHPqz5nDMiN5Jj9BeigjDkS2w010PvUnPkdVY3GerDFbY62TArtDBuDQ==",
             "dev": true,
             "requires": {
-                "@types/webpack": "*",
-                "terser": "^5.3.8"
+                "terser": "^5.3.8",
+                "webpack": "^5.1.0"
             }
         },
         "@types/uglify-js": {
@@ -818,9 +818,9 @@
             }
         },
         "electron-to-chromium": {
-            "version": "1.3.585",
-            "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.3.585.tgz",
-            "integrity": "sha512-xoeqjMQhgHDZM7FiglJAb2aeOxHZWFruUc3MbAGTgE7GB8rr5fTn1Sdh5THGuQtndU3GuXlu91ZKqRivxoCZ/A==",
+            "version": "1.3.587",
+            "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.3.587.tgz",
+            "integrity": "sha512-8XFNxzNj0R8HpTQslWAw6UWpGSuOKSP3srhyFHVbGUGb8vTHckZGCyWi+iQlaXJx5DNeTQTQLd6xN11WSckkmA==",
             "dev": true
         },
         "emoji-regex": {
@@ -1335,9 +1335,9 @@
             "dev": true
         },
         "jest-worker": {
-            "version": "26.6.1",
-            "resolved": "https://registry.npmjs.org/jest-worker/-/jest-worker-26.6.1.tgz",
-            "integrity": "sha512-R5IE3qSGz+QynJx8y+ICEkdI2OJ3RJjRQVEyCcFAd3yVhQSEtquziPO29Mlzgn07LOVE8u8jhJ1FqcwegiXWOw==",
+            "version": "26.6.2",
+            "resolved": "https://registry.npmjs.org/jest-worker/-/jest-worker-26.6.2.tgz",
+            "integrity": "sha512-KWYVV1c4i+jbMpaBC+U++4Va0cp8OisU185o73T1vo99hqi7w8tSJfUXYswwqqrjzwxa6KpRK54WhPvwf5w6PQ==",
             "dev": true,
             "requires": {
                 "@types/node": "*",
@@ -2191,9 +2191,9 @@
             }
         },
         "webpack": {
-            "version": "5.3.2",
-            "resolved": "https://registry.npmjs.org/webpack/-/webpack-5.3.2.tgz",
-            "integrity": "sha512-DXsfHoI6lQAR3KnQh7+FsRfs9fs+TEvzXCA35UbKv4kVuzslg7QCMAcpFRZNDMjdtm9N/PoO54XEzGN9TeacQg==",
+            "version": "5.4.0",
+            "resolved": "https://registry.npmjs.org/webpack/-/webpack-5.4.0.tgz",
+            "integrity": "sha512-udpYTyqz8toTTdaOsL2QKPLeZLt2IEm9qY7yTXuFEQhKu5bk0yQD9BtAdVQksmz4jFbbWOiWmm3NHarO0zr/ng==",
             "dev": true,
             "requires": {
                 "@types/eslint-scope": "^3.7.0",
diff --git a/package.json b/package.json
index 4c77a9f..fc885e2 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
     "icon": "assets/texinfo.png",
     "devDependencies": {
         "@types/node": "^14.14.6",
-        "@types/terser-webpack-plugin": "^5.0.1",
+        "@types/terser-webpack-plugin": "^5.0.2",
         "@types/vscode": "^1.50.0",
         "@types/webpack": "^4.41.24",
         "@typescript-eslint/eslint-plugin": "^3.8.0",
@@ -28,7 +28,7 @@
         "ts-loader": "^8.0.7",
         "ts-node": "^9.0.0",
         "typescript": "^4.0.5",
-        "webpack": "^5.3.2",
+        "webpack": "^5.4.0",
         "webpack-cli": "^4.1.0"
     },
     "scripts": {
diff --git a/src/contexts/document_symbol.ts b/src/contexts/document_symbol.ts
index 27a3346..a5e4be1 100644
--- a/src/contexts/document_symbol.ts
+++ b/src/contexts/document_symbol.ts
@@ -33,15 +33,13 @@ export default class DocumentSymbolContext {
      * Calculate document symbols based on folding ranges.
      */
     private calculcateDocumentSymbols() {
-        const ranges = Array<RangeNode>(this.document.lineCount);
+        const ranges = Array<Optional<FoldingRange>>(this.document.lineCount);
         this.documentContext.foldingRange.values.forEach(range => range.kind ?? (ranges[range.start] = range));
         return foldingRangeToSymbols(ranges, 0, ranges.length);
     }
 }
 
-type RangeNode = Optional<FoldingRange>;
-
-function foldingRangeToSymbols(ranges: readonly RangeNode[], start: number, end: number) {
+function foldingRangeToSymbols(ranges: readonly Optional<FoldingRange>[], start: number, end: number) {
     const symbols = <vscode.DocumentSymbol[]>[];
     for (let idx = start; idx < end; ++idx) {
         const node = ranges[idx];
diff --git a/webpack.config.ts b/webpack.config.ts
index 8a4f545..9cbb2e7 100644
--- a/webpack.config.ts
+++ b/webpack.config.ts
@@ -1,5 +1,6 @@
 import * as path from 'path';
 import * as webpack from 'webpack';
+import TerserPlugin from 'terser-webpack-plugin';
 
 const config: webpack.Configuration = {
     target: 'node',
@@ -14,6 +15,19 @@ const config: webpack.Configuration = {
     optimization: {
         concatenateModules: true,
         minimize: true,
+        minimizer: [
+            new TerserPlugin({
+                extractComments: false,
+                terserOptions: {
+                    compress: {
+                        unsafe: true,
+                    },
+                    format: {
+                        comments: false,
+                    },
+                },
+            }),
+        ],
     },
     externals: {
         vscode: 'commonjs vscode',