diff --git a/package-lock.json b/package-lock.json
index afcf855..5a95d6b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -455,6 +455,12 @@
       "integrity": "sha1-+PeLdniYiO858gXNY39o5wISKyw=",
       "dev": true
     },
+    "buffer-from": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.1.tgz",
+      "integrity": "sha512-MQcXEUbCKtEo7bhqEs6560Hyd4XaovZlO/k9V3hjVUF/zwW7KBVdSK4gIt/bzwS9MbR5qob+F5jusZsb0YQK2A==",
+      "dev": true
+    },
     "builtin-modules": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/builtin-modules/-/builtin-modules-1.1.1.tgz",
@@ -4118,6 +4124,24 @@
         "urix": "^0.1.0"
       }
     },
+    "source-map-support": {
+      "version": "0.5.12",
+      "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.12.tgz",
+      "integrity": "sha512-4h2Pbvyy15EE02G+JOZpUCmqWJuqrs+sEkzewTm++BPi7Hvn/HwcqLAcNxYAyI0x13CpPPn+kMjl+hplXMHITQ==",
+      "dev": true,
+      "requires": {
+        "buffer-from": "^1.0.0",
+        "source-map": "^0.6.0"
+      },
+      "dependencies": {
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
+      }
+    },
     "source-map-url": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/source-map-url/-/source-map-url-0.4.0.tgz",
@@ -4359,6 +4383,25 @@
         }
       }
     },
+    "terser": {
+      "version": "3.17.0",
+      "resolved": "https://registry.npmjs.org/terser/-/terser-3.17.0.tgz",
+      "integrity": "sha512-/FQzzPJmCpjAH9Xvk2paiWrFq+5M6aVOf+2KRbwhByISDX/EujxsK+BAvrhb6H+2rtrLCHK9N01wO014vrIwVQ==",
+      "dev": true,
+      "requires": {
+        "commander": "^2.19.0",
+        "source-map": "~0.6.1",
+        "source-map-support": "~0.5.10"
+      },
+      "dependencies": {
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
+      }
+    },
     "through": {
       "version": "2.3.8",
       "resolved": "https://registry.npmjs.org/through/-/through-2.3.8.tgz",
@@ -4496,6 +4539,7 @@
       "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.5.12.tgz",
       "integrity": "sha512-KeQesOpPiZNgVwJj8Ge3P4JYbQHUdZzpx6Fahy6eKAYRSV4zhVmLXoC+JtOeYxcHCHTve8RG1ZGdTvpeOUM26Q==",
       "dev": true,
+      "optional": true,
       "requires": {
         "commander": "~2.20.0",
         "source-map": "~0.6.1"
@@ -4505,7 +4549,8 @@
           "version": "0.6.1",
           "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
           "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
diff --git a/package.json b/package.json
index 1b2f928..1be92e1 100644
--- a/package.json
+++ b/package.json
@@ -32,8 +32,8 @@
     "remap-istanbul": "^0.13.0",
     "runjs": "^4.4.2",
     "shelljs": "^0.8.3",
-    "typescript": "^3.5.0-dev.20190516",
-    "uglify-js": "^3.5.12"
+    "terser": "^3.17.0",
+    "typescript": "^3.5.0-dev.20190516"
   },
   "dependencies": {
     "parse": "^2.4.0",
diff --git a/runfile.js b/runfile.js
index 68f96f1..83672f9 100644
--- a/runfile.js
+++ b/runfile.js
@@ -169,7 +169,7 @@ async function build() {
  */
 async function optimize() {
     // TODO do not overwrite dev build
-    await exec("uglifyjs out/app.js --source-map --ecma 6 --mangle --keep-classnames --compress --output out/app.js");
+    await exec("terser out/app.js --source-map --ecma 6 --mangle --keep-classnames --compress --output out/app.js");
 }
 
 /**
@@ -178,6 +178,7 @@ async function optimize() {
 async function deploy(task, experimental = false) {
     await build();
     await optimize();
+    shell.rm("-r", "out/coverage");
     await exec(`rsync -avz --delete ./out/ hosting.thunderk.net:/srv/website/spacetac${experimental ? "x" : ""}/`);
 }