diff --git a/src/TaskRunner.js b/src/TaskRunner.js
index 8f24332a..4e60a13a 100644
--- a/src/TaskRunner.js
+++ b/src/TaskRunner.js
@@ -14,7 +14,7 @@ export default class TaskRunner {
     const { cache, parallel } = options;
     this.cacheDir =
       cache === true
-        ? findCacheDir({ name: 'uglifyjs-webpack-plugin' })
+        ? findCacheDir({ name: 'uglifyjs-webpack-plugin' }) || os.tmpdir()
         : cache;
     // In some cases cpus() returns undefined
     // https://github.com/nodejs/node/issues/19022