diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 075f9c4e..aacb53b0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,7 +51,7 @@ jobs:
       - name: Build
         run: |
           mkdir ~/artifacts
-          docker run --rm -w /lib_xcore_math -v ${{ github.workspace }}:/lib_xcore_math -v ~/artifacts:/artifacts ghcr.io/xmos/xcore_builder:latest bash -l .github/scripts/build_tests_xcore.sh
+          docker run --rm -u $(id -u):$(id -g) -w /lib_xcore_math -v ${{ github.workspace }}:/lib_xcore_math -v ~/artifacts:/artifacts ghcr.io/xmos/xcore_builder:latest bash -l .github/scripts/build_tests_xcore.sh
 
       - name: Save Unit Test Artifacts
         uses: actions/upload-artifact@v2
@@ -134,4 +134,4 @@ jobs:
 
       - name: Build
         run: |
-          docker run --rm -w /lib_xcore_math -v ${{ github.workspace }}:/lib_xcore_math ghcr.io/xmos/xcore_builder:latest bash -l .github/scripts/build_legacy.sh
+          docker run --rm -u $(id -u):$(id -g) -w /lib_xcore_math -v ${{ github.workspace }}:/lib_xcore_math ghcr.io/xmos/xcore_builder:latest bash -l .github/scripts/build_legacy.sh