diff --git a/tests/javascripts/updateContent.test.js b/tests/javascripts/updateContent.test.js
index fdc620b74..0ea2d8d2d 100644
--- a/tests/javascripts/updateContent.test.js
+++ b/tests/javascripts/updateContent.test.js
@@ -145,6 +145,7 @@ describe('Update content', () => {
 
     expect($.ajax).toHaveBeenCalledTimes(1);
 
+    // units are milliseconds
     jest.advanceTimersByTime(500);
     jest.advanceTimersByTime(500);
     jest.advanceTimersByTime(500);
@@ -178,6 +179,7 @@ describe('Update content', () => {
 
       expect($.ajax).toHaveBeenCalledTimes(1);
 
+      // units are milliseconds
       jest.advanceTimersByTime(1500);
 
       expect($.ajax).toHaveBeenCalledTimes(2);