diff --git a/package.json b/package.json
index a76af509ed3e8..b0aaba2f81b25 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "build:clean": "run prepare",
     "docs": "run docs \"@theia/!(example-)*\"",
     "test": "yarn test:theia && yarn test:electron && yarn test:browser",
-    "test:theia": "run test \"@theia/!(example-)*\" --stream --concurrency 1",
+    "test:theia": "run test \"@theia/!(example-)*\" --stream --concurrency=1",
     "test:browser": "yarn rebuild:browser && run test \"@theia/example-browser\"",
     "test:electron": "yarn rebuild:electron && run test \"@theia/example-electron\"",
     "rebuild:clean": "rimraf .browser_modules",
diff --git a/scripts/lerna.js b/scripts/lerna.js
index 0bf533e2156ea..714f02fc4a1ec 100644
--- a/scripts/lerna.js
+++ b/scripts/lerna.js
@@ -19,9 +19,9 @@ const path = require('path');
 const lernaPath = path.resolve(__dirname, '..', 'node_modules', 'lerna', 'bin', 'lerna');
 
 if (process.platform === 'win32') {
-    console.log('Parallel lerna execution is disabled on Windows. Falling back to sequential execution with the \'--concurrency==1\' flag.');
-    if (process.argv.indexOf('--concurrency==1') === -1) {
-        process.argv.push('--concurrency==1');
+    console.log('Parallel lerna execution is disabled on Windows. Falling back to sequential execution with the \'--concurrency=1\' flag.');
+    if (process.argv.indexOf('--concurrency=1') === -1) {
+        process.argv.push('--concurrency=1');
     }
     const parallelIndex = process.argv.indexOf('--parallel');
     if (parallelIndex !== -1) {
@@ -29,4 +29,4 @@ if (process.platform === 'win32') {
     }
     console.log('Running lerna as: ' + process.argv.join(' '));
 }
-require(lernaPath);
\ No newline at end of file
+require(lernaPath);