diff --git a/script/cibuild b/script/cibuild
index 11b80fac..b126da23 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -3,7 +3,7 @@
 set -e
 
 bundle exec jekyll build
-bundle exec htmlproofer ./_site --check-html --check-sri
+bundle exec htmlproofer ./_site --check-html --check-sri --typhoeus-config='{"headers":{"User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/81.0"}}'
 bundle exec rubocop -D --config .rubocop.yml
 bundle exec script/validate-html
 gem build jekyll-theme-midnight.gemspec