diff --git a/pkgs/by-name/li/lightdm-slick-greeter/package.nix b/pkgs/by-name/li/lightdm-slick-greeter/package.nix
index ae76e71e78b5..b50a3188827e 100644
--- a/pkgs/by-name/li/lightdm-slick-greeter/package.nix
+++ b/pkgs/by-name/li/lightdm-slick-greeter/package.nix
@@ -83,7 +83,7 @@ stdenv.mkDerivation rec {
   '';
 
   preFixup = ''
-    buildPythonPath "$out $pythonPath"
+    buildPythonPath "$out ''${pythonPath[*]}"
     gappsWrapperArgs+=(
       --prefix PYTHONPATH : "$program_PYTHONPATH"
       --prefix XDG_DATA_DIRS : "${lib.makeSearchPath "share" [ xapp-symbolic-icons ]}"