diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 00d6509..c2ab948 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -12,6 +12,10 @@ jobs:
     steps:
     - uses: actions/checkout@v6
     - uses: cachix/install-nix-action@v31
+      with:
+        extra_nix_config: |
+          extra-substituters = https://cache.thalheim.io
+          extra-trusted-public-keys = cache.thalheim.io-1:R7msbosLEZKrxk/lKxf9BTjOOH7Ax3H0Qj0/6wiHOgc=
     - name: Add keys group (needed for go tests)
       run: sudo groupadd keys
     - name: Run unit tests