diff --git a/home/program/firefox/default.nix b/home/program/firefox/default.nix
index a4bef38b..59f746d1 100644
--- a/home/program/firefox/default.nix
+++ b/home/program/firefox/default.nix
@@ -38,7 +38,13 @@
 
 		// User agent.
 		// user_pref("general.useragent.override", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.61 Safari/537.36");
+
+		// Disable HTTP3.
 		user_pref("network.http.http3.enable", false)
+
+		// Disable built-in DoH.
+		user_pref("doh-rollout.disable-heuristics", true);
+		user_pref("network.trr.mode", 5);
 	'';
 
 	mkExtension = install_url: {