diff --git a/pkgs/applications/networking/mailreaders/betterbird/default.nix b/pkgs/applications/networking/mailreaders/betterbird/default.nix
index b479a01d0d4c..38ff368ad5fd 100644
--- a/pkgs/applications/networking/mailreaders/betterbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/betterbird/default.nix
@@ -112,6 +112,8 @@ in ((buildMozillaMach {
   webrtcSupport = false;
 
   pgoSupport = false; # console.warn: feeds: "downloadFeed: network connection unavailable"
+
+  inherit (thunderbird-unwrapped.passthru) icu73;
 }).overrideAttrs (oldAttrs: {
   postInstall = oldAttrs.postInstall or "" + ''
     mv $out/lib/thunderbird/* $out/lib/betterbird