diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 8f15af096..4feaf922c 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -41,6 +41,7 @@ jobs:
     defaults:
       run:
         shell: bash
+
     steps:
       - name: Cancel Previous Runs
         uses: styfle/cancel-workflow-action@0.13.0
@@ -89,18 +90,23 @@ jobs:
         run: uv sync --locked --group test --no-default-groups
 
       - name: Build module
-        run: uv run --no-default-groups python setup.py build_ext --inplace
+        run: uv run --locked --no-default-groups python setup.py build_ext --inplace
 
       - name: Fix windows gsl dlls
         if: matrix.os == 'windows-latest'
         run: cp /c/vcpkg/installed/x64-windows/bin/gsl*.dll msprime/
 
       - name: Run tests
-        run: uv run --no-default-groups pytest --cov=msprime --cov-report=xml --cov-branch -n2
+        run: |
+           uv run --locked --no-default-groups pytest --cov=msprime \
+            --cov-report=xml --cov-branch -n2
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v5.4.0
+        uses: codecov/codecov-action@v5.5.2
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
-          flags: python
-          fail_ci_if_error: true
+          fail_ci_if_error: false
+          flags: python-tests
+          files: coverage.xml
+          disable_search: true
+          verbose: true