diff --git a/pkgs/applications/networking/browsers/firefox/common.nix b/pkgs/applications/networking/browsers/firefox/common.nix
index 92434806a12d..988f47f3bfbb 100644
--- a/pkgs/applications/networking/browsers/firefox/common.nix
+++ b/pkgs/applications/networking/browsers/firefox/common.nix
@@ -386,4 +386,6 @@ buildStdenv.mkDerivation ({
 
   # on aarch64 this is also required
   dontUpdateAutotoolsGnuConfigScripts = true;
+
+  requiredSystemFeatures = [ "big-parallel" ];
 })
diff --git a/pkgs/applications/networking/mailreaders/thunderbird/default.nix b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
index 8295e8dbc871..fa229b8d7df4 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
@@ -321,6 +321,8 @@ stdenv.mkDerivation rec {
       gnugrep curl runtimeShell;
   };
 
+  requiredSystemFeatures = [ "big-parallel" ];
+
   meta = with stdenv.lib; {
     description = "A full-featured e-mail client";
     homepage = "https://www.thunderbird.net";