diff --git a/config/fontconfig/45-Hack.conf b/config/fontconfig/45-Hack.conf
index 88ab5403d..70b8d5c9c 100644
--- a/config/fontconfig/45-Hack.conf
+++ b/config/fontconfig/45-Hack.conf
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- Declare Hack a monospace font -->
   <alias>