diff --git a/tasks/build-distro.js b/tasks/build-distro.js
index 2fe30eeb..5c8dc928 100644
--- a/tasks/build-distro.js
+++ b/tasks/build-distro.js
@@ -23,10 +23,10 @@ del(dest);
 console.log('mkdir -p ' + dest);
 mkdirp(dest);
 
-console.log(`copy bpmn-font to ${dest}/bpmn-font`);
+console.log('copy bpmn-font to ' + dest + '/bpmn-font');
 cp(resolve('bpmn-font', '/dist/{font,css}/**'), dest + '/assets/bpmn-font');
 
-console.log(`copy diagram-js.css to ${dest}`);
+console.log('copy diagram-js.css to ' + dest);
 cp(resolve('diagram-js', '/assets/**'), dest + '/assets');
 
 bundle(dest, {
diff --git a/tasks/test-distro.js b/tasks/test-distro.js
index bfdb953b..c46e6bc6 100644
--- a/tasks/test-distro.js
+++ b/tasks/test-distro.js
@@ -9,7 +9,7 @@ function runTest(variant, env) {
   process.env.VARIANT = variant;
   process.env.NODE_ENV = env;
 
-  console.log(`[TEST] ${variant}@${env}`);
+  console.log('[TEST] ' + variant + '@' + env);
 
   try {
     execSync('karma', [ 'start', 'test/config/karma.distro.js' ]);
diff --git a/test/config/karma.distro.js b/test/config/karma.distro.js
index 5ff4e820..33a4d93b 100644
--- a/test/config/karma.distro.js
+++ b/test/config/karma.distro.js
@@ -37,13 +37,13 @@ module.exports = function(karma) {
     ],
 
     files: [
-      `dist/${VARIANT}.${NODE_ENV === 'production' ? 'production.min' : 'development'}.js`,
+      'dist/' + VARIANT + '.' + (NODE_ENV === 'production' ? 'production.min' : 'development') + '.js',
       'dist/assets/bpmn-font/css/bpmn.css',
       'dist/assets/diagram-js.css',
       { pattern: 'resources/initial.bpmn', included: false },
       { pattern: 'dist/assets/**/*', included: false },
       'test/distro/helper.js',
-      `test/distro/${VARIANT}.js`
+      'test/distro/' + VARIANT + '.js'
     ],
 
     reporters: [ 'spec' ],