diff --git a/test/chainsBuildTest.js b/test/chainsBuildTest.js
index 7e62e43b..de2fd426 100644
--- a/test/chainsBuildTest.js
+++ b/test/chainsBuildTest.js
@@ -6,7 +6,8 @@
  * @author Jonathan Olson <jonathan.olson@colorado.edu>
  */
 
-import execute from '../../perennial-alias/js/common/execute.js';
+// TODO: Convert chainsBuildTest.js to TypeScript and get rid of *.ts in the import, see https://github.com/phetsims/perennial/issues/410
+import execute from '../../perennial-alias/js/common/execute.ts';
 import gruntCommand from '../../perennial-alias/js/common/gruntCommand.js';
 import grunt from '../../perennial-alias/js/npm-dependencies/grunt.js';
 import qunit from '../../perennial-alias/js/npm-dependencies/qunit.js';
diff --git a/test/generationTest.js b/test/generationTest.js
index 1e06a3a5..b04216cd 100644
--- a/test/generationTest.js
+++ b/test/generationTest.js
@@ -6,7 +6,8 @@
  * @author Jonathan Olson <jonathan.olson@colorado.edu>
  */
 
-import execute from '../../perennial-alias/js/common/execute.js';
+// TODO: Convert generationTest.js to TypeScript and get rid of *.ts in the import, see https://github.com/phetsims/perennial/issues/410
+import execute from '../../perennial-alias/js/common/execute.ts';
 import gruntCommand from '../../perennial-alias/js/common/gruntCommand.js';
 import qunit from '../../perennial-alias/js/npm-dependencies/qunit.js';