diff --git a/images/nix-flakes/default.nix b/images/nix-flakes/default.nix
index 7bea3c9..9fb8673 100644
--- a/images/nix-flakes/default.nix
+++ b/images/nix-flakes/default.nix
@@ -12,6 +12,7 @@ docker-nixpkgs.nix.override {
       text = ''
         accept-flake-config = true
         experimental-features = nix-command flakes
+        max-jobs = auto
       '';
     })
   ] ++ extraContents;
diff --git a/images/nix-unstable-static/default.nix b/images/nix-unstable-static/default.nix
index f494ce0..a018073 100644
--- a/images/nix-unstable-static/default.nix
+++ b/images/nix-unstable-static/default.nix
@@ -84,11 +84,12 @@ let
     mkdir -p libexec/nix
     ln -s /bin/nix libexec/nix/build-remote
 
-    # Enable flakes
+    # Enable flakes and parallel building
     mkdir -p etc/nix
     cat <<NIX_CONFIG > etc/nix/nix.conf
     accept-flake-config = true
     experimental-features = nix-command flakes
+    max-jobs = auto
     NIX_CONFIG
 
     # Add run-as-user script