diff --git a/overlays/bmxd.nix b/overlays/bmxd.nix
index 8a4e9324..4bec93ed 100644
--- a/overlays/bmxd.nix
+++ b/overlays/bmxd.nix
@@ -1,20 +1,21 @@
-{ stdenv, fetchgit }:
+{ stdenv, fetchgit, writeScript, runtimeShell }:
 
 stdenv.mkDerivation {
   pname = "bmxd";
-  version = "1.1-2"; # ${version}-${release}
+  version = "1.1-freifunk-dresden-c3d2";
 
   src = fetchgit {
     url = "https://gitlab.freifunk-dresden.de/firmware-developer/firmware.git";
-    rev = "T_FIRMWARE_7.0.3";
-    sha256 = "sha256-LPlsfZvi0Hs9h0IM8Xtiv8GkkVLWs8LL+XSewTT+XHA=";
+    rev = "T_FIRMWARE_8.1.5";
+    sha256 = "sha256-DEz9KROKhOSdp0XPvkpV5DCTN06FxIMj2YaVKC0hkyo=";
   };
 
-  buildPhase = ''
+  preBuild = ''
     cd feeds/common/bmxd/sources
   '';
 
-  installFlags = [
-    "SBINDIR=${placeholder "out"}/sbin"
-  ];
+  installPhase = ''
+    mkdir -p $out/sbin
+    cp bmxd $out/sbin
+  '';
 }