diff --git a/pkgs/build-support/build-fhs-userenv/default.nix b/pkgs/build-support/build-fhs-userenv/default.nix
index aa95080ac52d..54ce3e768975 100644
--- a/pkgs/build-support/build-fhs-userenv/default.nix
+++ b/pkgs/build-support/build-fhs-userenv/default.nix
@@ -1,8 +1,9 @@
-{ runCommand, lib, writeText, writeScriptBin, stdenv, ruby } :
-{ env, runScript ? "bash", extraBindMounts ? [], extraInstallCommands ? "" } :
+{ runCommand, lib, writeText, writeScriptBin, stdenv, bash, ruby } :
+{ env, runScript ? "${bash}/bin/bash", extraBindMounts ? [], extraInstallCommands ? "" } :
 
 let
   name = env.pname;
+  bash' = "${bash}/bin/bash";
 
   # Sandboxing script
   chroot-user = writeScriptBin "chroot-user" ''
@@ -29,7 +30,7 @@ in runCommand name {
     runCommand "${name}-shell-env" {
       shellHook = ''
         export CHROOTENV_EXTRA_BINDS="${lib.concatStringsSep ":" extraBindMounts}:$CHROOTENV_EXTRA_BINDS"
-        exec ${chroot-user}/bin/chroot-user ${env} bash -l ${init "bash"} "$(pwd)"
+        exec ${chroot-user}/bin/chroot-user ${env} ${bash'} -l ${init bash'} "$(pwd)"
       '';
     } ''
       echo >&2 ""
@@ -42,7 +43,7 @@ in runCommand name {
   cat <<EOF >$out/bin/${name}
   #! ${stdenv.shell}
   export CHROOTENV_EXTRA_BINDS="${lib.concatStringsSep ":" extraBindMounts}:\$CHROOTENV_EXTRA_BINDS"
-  exec ${chroot-user}/bin/chroot-user ${env} bash -l ${init runScript} "\$(pwd)" "\$@"
+  exec ${chroot-user}/bin/chroot-user ${env} ${bash'} -l ${init runScript} "\$(pwd)" "\$@"
   EOF
   chmod +x $out/bin/${name}
   ${extraInstallCommands}