diff --git a/packages/react-dom/src/__tests__/ReactMount-test.js b/packages/react-dom/src/__tests__/ReactMount-test.js
index ef87fbac73..e99db093d5 100644
--- a/packages/react-dom/src/__tests__/ReactMount-test.js
+++ b/packages/react-dom/src/__tests__/ReactMount-test.js
@@ -302,7 +302,7 @@ describe('ReactMount', () => {
       ReactDOM.render(<Foo>a</Foo>, container2);
       // The update did not flush yet.
       expect(container1.textContent).toEqual('1');
-      // The initial mount flushed, but not the update scheduled in cDU.
+      // The initial mount flushed, but not the update scheduled in cDM.
       expect(container2.textContent).toEqual('a');
     });
     // All updates have flushed.