diff --git a/nixos/lib/make-squashfs.nix b/nixos/lib/make-squashfs.nix
index 8690c42e7ac9..170d315fb751 100644
--- a/nixos/lib/make-squashfs.nix
+++ b/nixos/lib/make-squashfs.nix
@@ -21,8 +21,15 @@ stdenv.mkDerivation {
       # for nix-store --load-db.
       cp $closureInfo/registration nix-path-registration
 
+      # 64 cores on i686 does not work
+      # fails with FATAL ERROR: mangle2:: xz compress failed with error code 5
+      if ((NIX_BUILD_CORES > 48)); then
+        NIX_BUILD_CORES=48
+      fi
+
       # Generate the squashfs image.
       mksquashfs nix-path-registration $(cat $closureInfo/store-paths) $out \
-        -no-hardlinks -keep-as-directory -all-root -b 1048576 -comp ${comp}
+        -no-hardlinks -keep-as-directory -all-root -b 1048576 -comp ${comp} \
+        -processors $NIX_BUILD_CORES
     '';
 }