diff --git a/lib/utils/result-summary.js b/lib/utils/result-summary.js
index 1c88baf1..36d419ce 100644
--- a/lib/utils/result-summary.js
+++ b/lib/utils/result-summary.js
@@ -1,10 +1,14 @@
 'use strict';
 
-const CoreObject = require('core-object');
 const chalk = require('chalk');
 const Table = require('cli-table3');
 
-module.exports = CoreObject.extend({
+module.exports = class ResultSummary {
+  constructor(options) {
+    this.results = options.results;
+    this.ui = options.ui;
+  }
+
   print() {
     let task = this;
     let colorAndMessage;
@@ -39,13 +43,15 @@ module.exports = CoreObject.extend({
 
     task.ui.writeLine('');
     task._printResultsSummary(countFailed, countPassed, allowedFailCount, this.results.length);
-  },
+  }
+
   _printResultHeader() {
     let task = this;
     task.ui.writeLine('');
     task.ui.writeLine('------ RESULTS ------');
     task.ui.writeLine('');
-  },
+  }
+
   _printDependencyTable(dependencyStatus) {
     if (!dependencyStatus.length) {
       return;
@@ -80,7 +86,8 @@ module.exports = CoreObject.extend({
     });
     task.ui.writeLine(table);
     task.ui.writeLine('');
-  },
+  }
+
   _printResultsSummary(countFailed, countPassed, allowedFailCount, total) {
     let task = this;
     if (countFailed) {
@@ -94,5 +101,5 @@ module.exports = CoreObject.extend({
     } else {
       task.ui.writeLine(chalk.green(`All ${countPassed} scenarios succeeded`));
     }
-  },
-});
+  }
+};
diff --git a/lib/utils/scenario-manager.js b/lib/utils/scenario-manager.js
index 8882caa7..9084d2fe 100644
--- a/lib/utils/scenario-manager.js
+++ b/lib/utils/scenario-manager.js
@@ -1,15 +1,18 @@
 'use strict';
 
-const CoreObject = require('core-object');
+module.exports = class ScenarioManager {
+  constructor(options) {
+    this.dependencyManagerAdapters = options.dependencyManagerAdapters;
+    this.ui = options.ui;
+  }
 
-module.exports = CoreObject.extend({
   async setup() {
     let { ui } = this;
 
     for (let depManager of this.dependencyManagerAdapters) {
       await depManager.setup({ ui });
     }
-  },
+  }
 
   async changeTo(scenario) {
     let results = [];
@@ -23,11 +26,11 @@ module.exports = CoreObject.extend({
     }
 
     return results;
-  },
+  }
 
   async cleanup() {
     for (let depManager of this.dependencyManagerAdapters) {
       await depManager.cleanup();
     }
-  },
-});
+  }
+};