diff --git a/etc/fonts/conf.d/70-no-bitmaps-firefox.conf b/etc/fonts/conf.d/70-no-bitmaps-firefox.conf
new file mode 100644
index 0000000..2862ae7
--- /dev/null
+++ b/etc/fonts/conf.d/70-no-bitmaps-firefox.conf
@@ -0,0 +1,19 @@
+<?xml version='1.0'?>
+<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+<fontconfig>
+  <!-- Disable bitmap fonts for Firefox/pdf.js to work around https://bugzilla.mozilla.org/show_bug.cgi?id=1839860 -->
+
+  <match>
+    <test qual="all" name="prgname" target="pattern" compare="eq">
+      <string>firefox</string>
+    </test>
+
+   <selectfont>
+     <rejectfont>
+       <pattern>
+         <patelt name="scalable"><bool>false</bool></patelt>
+       </pattern>
+     </rejectfont>
+   </selectfont>
+  </match>
+</fontconfig>