diff --git a/pkgs/misc/busybox/default.nix b/pkgs/misc/busybox/default.nix
index 1ae51d64e30..f4980935c86 100644
--- a/pkgs/misc/busybox/default.nix
+++ b/pkgs/misc/busybox/default.nix
@@ -1,4 +1,4 @@
-{stdenv, fetchurl, enableStatic ? false, extraConfig ? null}:
+{stdenv, fetchurl, enableStatic ? false, extraConfig ? ""}:
 
 let
   configParser = ''