diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 98b4a9e7a..14204c6a0 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -355,11 +355,26 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-            toolchain: nightly
-      - name: Install tarpaulin
-        run: cargo +nightly install cargo-tarpaulin
-      - name: Run tarpaulin
-        run: cargo tarpaulin --no-dead-code --engine llvm --workspace --all-features --ignore-panics --out Lcov
+            toolchain: stable
+      - name: Run for coverage
+        run: |
+          sudo apt-get update
+          sudo apt-get install lcov -y
+          rustup component add llvm-tools-preview
+          cargo install grcov
+          export RUSTFLAGS="-Cinstrument-coverage"
+          export LLVM_PROFILE_FILE=$(pwd)/target/clvm_tools_rs-%p-%m.profraw
+          export CARGO_TARGET_DIR=$(pwd)/target
+          cargo test --release --workspace
+          python -m venv venv
+          source venv/bin/activate
+          git clone https://github.com/Chia-Network/clvm_tools.git --branch=main --single-branch
+          pip install ./clvm_tools
+          pip install maturin pytest
+          maturin develop --release
+          (cd resources/tests/cmdline/tests && pytest)
+          grcov . --binary-path target -s . --branch --ignore-not-existing --ignore='*/.cargo/*' --ignore='*/tests/*' -o rust_cov.info
+          python -c 'with open("rust_cov.info") as f: lines = [l for l in f if not (l.startswith("DA:") and int(l.split(",")[1].strip()) >= 2**63)]; open("lcov.info", "w").writelines(lines)'
       - name: Upload to Coveralls
         uses: coverallsapp/github-action@v2
         if: always()
diff --git a/src/compiler/rename.rs b/src/compiler/rename.rs
index 1229543cf..c9401f85d 100644
--- a/src/compiler/rename.rs
+++ b/src/compiler/rename.rs
@@ -240,7 +240,9 @@ fn rename_in_bodyform(
                 },
                 vs,
             )?;
-            // First element of call is the function, which is not renamed.
+            // Ensure that we haven't renamed the 0th element of a call
+            // They exist in a separate (global) namespace of callables
+            // and aren't in the variable scope stack.
             if !vs.is_empty() {
                 new_vs[0] = vs[0].clone();
             }