diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 877e18a43a..85d5359f9a 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1395,6 +1395,8 @@ pref("network.protocol-handler.external.shell", false);
 pref("network.protocol-handler.external.vbscript", false);
 pref("network.protocol-handler.external.vnd.ms.radio", false);
 #ifdef XP_WIN
+pref("network.protocol-handler.external.ms-cxh", false);
+pref("network.protocol-handler.external.ms-cxh-full", false);
 pref("network.protocol-handler.external.ms-help", false);
 pref("network.protocol-handler.external.ms-msdt", false);
 pref("network.protocol-handler.external.search", false);