diff --git a/blog/convert.rb b/blog/convert.rb
index bb74a36..e8460d1 100644
--- a/blog/convert.rb
+++ b/blog/convert.rb
@@ -31,5 +31,5 @@ files.each do |file|
   document.search('//*[not(ancestor-or-self::code)]/text()').each do |t|
     t.replace(perform_katex_sub(inline_cache, display_cache, t.content))
   end
-  File.write(file, document.to_html)
+  File.write(file, document.to_html(encoding: 'US-ASCII'))
 end