diff --git a/.github/workflows/regression-tests.yml b/.github/workflows/regression-tests.yml
index 006c1c08..f1b3f403 100644
--- a/.github/workflows/regression-tests.yml
+++ b/.github/workflows/regression-tests.yml
@@ -8,6 +8,9 @@ on:
     branches:
     - master
 
+permissions:
+  contents: read
+
 jobs:
 
   pre-commit:
@@ -18,11 +21,16 @@ jobs:
       with:
         python-version: "3.12"
     - uses: pre-commit/action@v3.0.1
+      env:
+        SKIP: coverage # Run all normal formatting hooks in CI, but skip the local coverage hook because the coverage job handles it separately.
 
   tests:
 
     name: Python ${{matrix.python-version}} | ${{matrix.sim}}
     runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      checks: write
     env:
       SIM: ${{matrix.sim}}
 
@@ -42,6 +50,7 @@ jobs:
 
           - sim: icarus
             python-version: '3.13'
+            coverage: true
 
           - sim: verilator
             sim-version: 5.044
@@ -50,6 +59,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v6
+      with:
+        fetch-depth: ${{ matrix.coverage && '0' || '1' }}
     - name: Set up miniforge ${{matrix.python-version}}
       uses: conda-incubator/setup-miniconda@v3
       with:
@@ -71,7 +82,13 @@ jobs:
     - name: Install Python dependencies
       shell: bash -l {0}
       run: |
-        pip install pyvisa pyvisa-sim pytest coverage coveralls pytest-cov cocotb>=2 cocotb-bus
+        pip install pyvisa pyvisa-sim pytest cocotb>=2 cocotb-bus
+
+    - name: Install coverage dependency
+      if: matrix.coverage
+      shell: bash -l {0}
+      run: |
+        pip install coverage diff-cover
 
     - name: Install basil
       shell: bash -l {0}
@@ -79,13 +96,49 @@ jobs:
         pip install -e .
 
     - name: Test
+      if: ${{ !matrix.coverage }}
       shell: bash -l {0}
       run: |
-        pytest ${{matrix.pytest-marker}} --cov=basil tests/test_*.py examples/*/*/test_*.py
+        pytest ${{matrix.pytest-marker}} tests/test_*.py examples/*/*/test_*.py
 
-    - name: Upload to codecov
+    - name: Test with coverage
+      if: matrix.coverage
+      shell: bash -l {0}
+      run: |
+        coverage run --source=basil -m pytest ${{matrix.pytest-marker}} \
+          tests/test_*.py examples/*/*/test_*.py
+        coverage xml -o coverage.xml
+        coverage report --format=total | awk '{print "### Test coverage: " $1 "%"}' >> "$GITHUB_STEP_SUMMARY"
+
+    - name: Create differential coverage report
+      if: matrix.coverage && github.event_name == 'pull_request'
+      env:
+        BASE_REF: ${{github.base_ref}}
       shell: bash -l {0}
       run: |
-        curl -Os https://uploader.codecov.io/latest/linux/codecov
-        chmod +x codecov
-        ./codecov -t ${CODECOV_TOKEN}
+        diff-cover coverage.xml \
+          --compare-branch="origin/${BASE_REF}" \
+          --format=markdown:diff-cover.md
+        cat diff-cover.md >> "$GITHUB_STEP_SUMMARY"
+
+    - name: Publish differential coverage check
+      if: >-
+        matrix.coverage &&
+        github.event_name == 'pull_request' &&
+        github.event.pull_request.head.repo.full_name == github.repository
+      continue-on-error: true
+      env:
+        GH_TOKEN: ${{github.token}}
+        HEAD_SHA: ${{github.event.pull_request.head.sha}}
+      run: |
+        gh api --method POST \
+          --header "Accept: application/vnd.github+json" \
+          --header "X-GitHub-Api-Version: 2022-11-28" \
+          "repos/${GITHUB_REPOSITORY}/check-runs" \
+          --raw-field name="Coverage (informational)" \
+          --raw-field head_sha="$HEAD_SHA" \
+          --raw-field status=completed \
+          --raw-field conclusion=neutral \
+          --raw-field "output[title]=Differential coverage" \
+          --field "output[summary]=@diff-cover.md" \
+          --silent
diff --git a/.gitignore b/.gitignore
index 68bb5bfb..dfbb7b14 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,6 +41,10 @@ Makefile
 *.out
 examples/lx9/device/src/SiTCP
 
+# Test coverage
+.coverage
+coverage.xml
+
 # PyDev files
 .project
 .pydevproject
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 32c39dfc..1f81974f 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -15,3 +15,21 @@ repos:
     hooks:
     -   id: end-of-file-fixer
     -   id: trailing-whitespace
+  - repo: local
+    hooks:
+      - id: coverage
+        name: Coverage
+        entry: >-
+          bash -c 'SIM=icarus coverage run
+          --source=basil -m pytest
+          -q --disable-warnings
+          tests/test_*.py examples/*/*/test_*.py
+          && coverage xml -q -o coverage.xml
+          && diff-cover coverage.xml
+          --compare-branch=origin/master
+          --show-uncovered'
+        language: system
+        pass_filenames: false
+        verbose: true
+        files: ^(basil/|tests/|examples/).*\.py$
+        stages: [pre-commit]
diff --git a/pyproject.toml b/pyproject.toml
index d05e1e4a..d531dd86 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,12 +38,11 @@ hw = ["pyserial", "PyVISA"]
 
 test = [
     "coverage",
-    "coveralls",
     "cocotb>=2.0.1",
     "cocotb-bus>=0.3.0",
     "cocotb-test>=0.2.6",
+    "diff-cover",
     "pytest>=9.0.3",
-    "pytest-cov",
     "PyVISA",
     "pyvisa-sim",
 ]