diff --git a/pkgs/servers/klipper/default.nix b/pkgs/servers/klipper/default.nix
index 3f29dc4f14f..3ebc09aa541 100644
--- a/pkgs/servers/klipper/default.nix
+++ b/pkgs/servers/klipper/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   # NB: This is needed for the postBuild step
   nativeBuildInputs = [ (python3.withPackages ( p: with p; [ cffi ] )) ];
 
-  buildInputs = [ (python3.withPackages (p: with p; [ cffi pyserial greenlet jinja2 markupsafe ])) ];
+  buildInputs = [ (python3.withPackages (p: with p; [ cffi pyserial greenlet jinja2 markupsafe numpy ])) ];
 
   # we need to run this to prebuild the chelper.
   postBuild = ''