diff --git a/packages/stryker/test/unit/SandboxPoolSpec.ts b/packages/stryker/test/unit/SandboxPoolSpec.ts
index 01321e84c4..6984ce3b8a 100644
--- a/packages/stryker/test/unit/SandboxPoolSpec.ts
+++ b/packages/stryker/test/unit/SandboxPoolSpec.ts
@@ -10,6 +10,7 @@ import { Task } from '../../src/utils/Task';
 import '../helpers/globals';
 import { Mock, config, file, mock, testFramework } from '../helpers/producers';
 import LoggingClientContext from '../../src/logging/LoggingClientContext';
+import { sleep } from '../../src/utils/objectUtils';
 
 const OVERHEAD_TIME_MS = 42;
 const LOGGING_CONTEXT: LoggingClientContext = Object.freeze({
@@ -117,8 +118,6 @@ describe('SandboxPool', () => {
 });
 
 function tick() {
-  return new Promise(res => {
-    setTimeout(res, 0);
-  });
+  return sleep(0);
 }
 
diff --git a/packages/stryker/test/unit/transpiler/MutantTranspilerSpec.ts b/packages/stryker/test/unit/transpiler/MutantTranspilerSpec.ts
index 58943dce1b..2d274128a6 100644
--- a/packages/stryker/test/unit/transpiler/MutantTranspilerSpec.ts
+++ b/packages/stryker/test/unit/transpiler/MutantTranspilerSpec.ts
@@ -6,7 +6,7 @@ import ChildProcessProxy from '../../../src/child-proxy/ChildProcessProxy';
 import MutantTranspiler from '../../../src/transpiler/MutantTranspiler';
 import TranspileResult from '../../../src/transpiler/TranspileResult';
 import TranspilerFacade, * as transpilerFacade from '../../../src/transpiler/TranspilerFacade';
-import { errorToString } from '../../../src/utils/objectUtils';
+import { errorToString, sleep } from '../../../src/utils/objectUtils';
 import '../../helpers/globals';
 import { Mock, config, file, mock, testableMutant } from '../../helpers/producers';
 import LoggingClientContext from '../../../src/logging/LoggingClientContext';
@@ -157,9 +157,7 @@ describe('MutantTranspiler', () => {
         ];
         expect(actualResults).deep.eq(expectedResults);
       });
-      const nextTick = () => new Promise(res => {
-        setTimeout(res, 0);
-      });
+      const nextTick = () => sleep(0);
     });
   });