diff --git a/src/build.sh b/src/build.sh
index ac0c0f9..af6212f 100644
--- a/src/build.sh
+++ b/src/build.sh
@@ -1,7 +1,8 @@
 #!/usr/bin/env nix-shell
 #! nix-shell -i bash
 #! nix-shell -p bash curl gcc zlib libffi icu77
-VERSION="140.4.0esr"
+SUBVERSION="140.4.0"
+VERSION="$SUBVERSIONesr"
 DOWNLOAD="https://ftp.mozilla.org/pub/firefox/releases/$VERSION/source/firefox-$VERSION.source.tar.xz"
 BUILDPATH=$(realpath .)
 mkdir bin