diff --git a/package-lock.json b/package-lock.json
index 549aada3..6fd16c9b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6183,9 +6183,9 @@
       "dev": true
     },
     "husky": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/husky/-/husky-2.2.0.tgz",
-      "integrity": "sha512-lG33E7zq6v//H/DQIojPEi1ZL9ebPFt3MxUMD8MR0lrS2ljEPiuUUxlziKIs/o9EafF0chL7bAtLQkcPvXmdnA==",
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/husky/-/husky-2.3.0.tgz",
+      "integrity": "sha512-A/ZQSEILoq+mQM3yC3RIBSaw1bYXdkKnyyKVSUiJl+iBjVZc5LQEXdGY1ZjrDxC4IzfRPiJ0IqzEQGCN5TQa/A==",
       "dev": true,
       "requires": {
         "cosmiconfig": "^5.2.0",
@@ -6195,9 +6195,9 @@
         "is-ci": "^2.0.0",
         "pkg-dir": "^4.1.0",
         "please-upgrade-node": "^3.1.1",
-        "read-pkg": "^5.0.0",
+        "read-pkg": "^5.1.1",
         "run-node": "^1.0.0",
-        "slash": "^2.0.0"
+        "slash": "^3.0.0"
       },
       "dependencies": {
         "pkg-dir": {
@@ -6220,6 +6220,12 @@
             "parse-json": "^4.0.0",
             "type-fest": "^0.4.1"
           }
+        },
+        "slash": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/slash/-/slash-3.0.0.tgz",
+          "integrity": "sha512-g9Q1haeby36OSStwb4ntCGGGaKsaVSjQ68fBxoQcutl5fS1vuY18H3wSt3jFyFtrkx+Kz0V1G85A4MyAdDMi2Q==",
+          "dev": true
         }
       }
     },
@@ -6701,8 +6707,7 @@
     "is-wsl": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/is-wsl/-/is-wsl-1.1.0.tgz",
-      "integrity": "sha1-HxbkqiKwTRM2tmGIpmrzxgDDpm0=",
-      "dev": true
+      "integrity": "sha1-HxbkqiKwTRM2tmGIpmrzxgDDpm0="
     },
     "isarray": {
       "version": "1.0.0",
diff --git a/package.json b/package.json
index ef4bc006..ee0be3d0 100644
--- a/package.json
+++ b/package.json
@@ -37,6 +37,7 @@
   "dependencies": {
     "cacache": "^11.3.2",
     "find-cache-dir": "^2.0.0",
+    "is-wsl": "^1.1.0",
     "schema-utils": "^1.0.0",
     "serialize-javascript": "^1.7.0",
     "source-map": "^0.6.1",
diff --git a/src/TaskRunner.js b/src/TaskRunner.js
index 2c625b6b..87b4c580 100644
--- a/src/TaskRunner.js
+++ b/src/TaskRunner.js
@@ -4,6 +4,7 @@ import cacache from 'cacache';
 import findCacheDir from 'find-cache-dir';
 import workerFarm from 'worker-farm';
 import serialize from 'serialize-javascript';
+import isWsl from 'is-wsl';
 
 import minify from './minify';
 
@@ -19,10 +20,13 @@ export default class TaskRunner {
     // In some cases cpus() returns undefined
     // https://github.com/nodejs/node/issues/19022
     const cpus = os.cpus() || { length: 1 };
-    this.maxConcurrentWorkers =
-      parallel === true
-        ? cpus.length - 1
-        : Math.min(Number(parallel) || 0, cpus.length - 1);
+    // WSL sometimes freezes, error seems to be on the WSL side
+    // https://github.com/webpack-contrib/terser-webpack-plugin/issues/21
+    this.maxConcurrentWorkers = isWsl
+      ? 1
+      : parallel === true
+      ? cpus.length - 1
+      : Math.min(Number(parallel) || 0, cpus.length - 1);
   }
 
   run(tasks, callback) {