diff --git a/nixos/modules/programs/fish.nix b/nixos/modules/programs/fish.nix
index 8b78d3d9e2b2..c85097f45e92 100644
--- a/nixos/modules/programs/fish.nix
+++ b/nixos/modules/programs/fish.nix
@@ -271,7 +271,7 @@ in
             ''
               mkdir -p $out
               if [ -d $package/share/man ]; then
-                find $package/share/man -type f | xargs ${pkgs.python3.interpreter} ${patchedGenerator}/create_manpage_completions.py --directory $out >/dev/null
+                find $package/share/man -type f | xargs ${pkgs.python3.pythonForBuild.interpreter} ${patchedGenerator}/create_manpage_completions.py --directory $out >/dev/null
               fi
             '';
         in