diff --git a/.github/workflows/check-and-ebook.yml b/.github/workflows/check-and-ebook.yml
index c677750fb..ff9c5824b 100644
--- a/.github/workflows/check-and-ebook.yml
+++ b/.github/workflows/check-and-ebook.yml
@@ -127,7 +127,7 @@ jobs:
 
       - name: Compare to previous hpmor.html
         run: |
-          diff -u hpmor-prev.html hpmor.html > hpmor-html-diff.log || :
+          diff -u -s hpmor-prev.html hpmor.html > hpmor-html-diff.log || :
           rm hpmor-prev.html
 
       - name: ls after