diff --git a/pkgs/os-specific/linux/kernel/linux-2.6.20.nix b/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
index 53cafe604a83..8e9357001066 100644
--- a/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
+++ b/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
@@ -40,7 +40,7 @@ stdenv.mkDerivation {
     if stdenv.system == "x86_64-linux" then "x86_64" else
     abort "";
 
-  makeFlags = if userModeLinux then "ARCH=um" else "";
+  makeFlags = if userModeLinux then "ARCH=um SHELL=bash" else "";
 
   inherit module_init_tools;