diff --git a/.github/actions/build-action/Dockerfile b/.github/actions/build-action/Dockerfile
index b623b2a..651fbe1 100644
--- a/.github/actions/build-action/Dockerfile
+++ b/.github/actions/build-action/Dockerfile
@@ -5,12 +5,17 @@
 # Container image that runs your code
 FROM ubuntu:22.04
 
+ARG USER=builder
+
 ENV TZ=Europe/Helsinki
 ENV LANG=en_US.utf8
 
 RUN apt-get update && apt-get -y install curl xz-utils git
 
-# Install nixos
+RUN groupadd nix
+RUN useradd -m -d /home/${USER} -s /bin/bash -G nix ${USER}
+
+# Install nix
 COPY ./installer.conf /tmp/installer.conf
 #COPY install_nix.sh /install_nix.sh
 #RUN /install_nix.sh
@@ -23,6 +28,8 @@ RUN curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/
 RUN rm -f /tmp/installer.conf
 ENV PATH="${PATH}:/nix/var/nix/profiles/default/bin"
 
+USER ${USER}
+
 # Copies your code file from your action repository to the filesystem path `/` of the container
 COPY entrypoint.sh /entrypoint.sh
 
diff --git a/.github/actions/build-action/installer.conf b/.github/actions/build-action/installer.conf
index 5d4ca4f..3a25767 100644
--- a/.github/actions/build-action/installer.conf
+++ b/.github/actions/build-action/installer.conf
@@ -1,3 +1,5 @@
+trusted-users = root @nix
+allowed-users = root @nix
 extra-system-features = kvm
 sandbox = false
 show-trace = true
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index d669e7e..5f69848 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -77,15 +77,34 @@ jobs:
           large-packages: true
           docker-images: true
           swap-storage: true
-      - name: Build
-        id: build
-        uses: ./.github/actions/build-action
-        env:
-          FMO_BUILD_VERSION: "${{ steps.fmo-build-version.outputs.BUILD_VERSION }}"
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
         with:
-          BUILD_TARGET: "fmo-os-installer-debug"
-          CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
-          RA_TOKEN: ${{ secrets.RA_TOKEN }}
+          name: fmo-os
+          authToken: '${{ secrets.CACHIX_TOKEN }}'
+          nix_path: nixpkgs=channel:nixos-unstable
+          enable_kvm: true
+          extra_nix_config: |
+            show-trace = true
+            max-jobs = auto
+            cores = 0
+            substitute = true
+            always-allow-substitute = true
+            substituters = https://cache.nixos.org https://nixpkgs.cachix.org https://nixpkgs-unfree.cachix.org https://nix-community.cachix.org
+            trusted-substituters = https://cache.nixos.org https://nixpkgs.cachix.org https://nixpkgs-unfree.cachix.org https://nix-community.cachix.org
+            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nixpkgs.cachix.org-1:q91R6hxbwFvDqTSDKwDAV4T5PxqXGxswD8vhONFMeOE= nixpkgs-unfree.cachix.org-1:hqvoInulhbV4nJ9yJOEr+4wxhDV4xq2d1DK7S6Nj6rs= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=
+        run: |
+          nix run nixpkgs#hello
+          nix flake show
+      #- name: Build
+      #  id: build
+      #  uses: ./.github/actions/build-action
+      #  env:
+      #    FMO_BUILD_VERSION: "${{ steps.fmo-build-version.outputs.BUILD_VERSION }}"
+      #  with:
+      #    BUILD_TARGET: "fmo-os-installer-debug"
+      #    CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
+      #    RA_TOKEN: ${{ secrets.RA_TOKEN }}
       #- name: Push to JFrog artifactory
       #  uses: ./.github/actions/upload-action-jfrog
       #  with: