diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index d52de21..5a3d69e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -16,12 +16,14 @@ jobs:
             # oldest LLVM that the install-llvm-action action is able to install
             description: "LLVM 5"
             llvm-version: "5"
+            #gcov_executable: "llvm-cov gcov"
 
           - os: ubuntu-22.04
             # select libc++ as libstdc++ appears to be the default
             description: "LLVM 16 libc++"
             llvm-version: "16"
             cmake-flags: '-DCMAKE_CXX_FLAGS="-stdlib=libc++" -DCMAKE_EXE_LINKER_FLAGS="-lc++abi"'
+            #gcov_executable: "llvm-cov gcov"
 
           - os: ubuntu-20.04
             description: "GCC 7"
@@ -32,6 +34,7 @@ jobs:
           - os: ubuntu-20.04
             description: "GCC 9"
             gcc-version: "9"
+            #gcov_executable: "gcov"
 
           - os: ubuntu-latest
             description: "GCC 13"
@@ -45,6 +48,7 @@ jobs:
 
           - os: ubuntu-latest
             # default GCC, which has gcov
+            gcov_executable: "gcov"
 
           - os: macos-latest
             # uses Apple Clang
@@ -117,6 +121,13 @@ jobs:
           echo "Supplement Test:"
           ./supplement_test || ./Debug/supplement_test.exe || node supplement_test
         shell: bash
+      
+      - name: Create code coverage report (gcov)
+        if: matrix.gcov_executable != ''
+        working-directory: ./build/tests
+        run: |
+          pip install gcovr
+          gcovr --delete --root ../../ --print-summary --xml coverage.xml . --gcov-executable '${{ matrix.gcov_executable }}' --merge-mode-functions=separate --gcov-ignore-parse-errors=negative_hits.warn_once_per_file
 
       - name: Benchmark
         # Earliest GCC with all benchmarked methods is 9
@@ -145,8 +156,9 @@ jobs:
         shell: bash
 
       - name: Upload Coverage to Codecov
-        if: contains(matrix.os, 'ubuntu') || contains(matrix.os, 'macos')
-        uses: codecov/codecov-action@v3
+        if: matrix.gcov_executable != ''
+        uses: codecov/codecov-action@v4
         with:
-          gcov: true
-          gcov_include: include/*
+          fail_ci_if_error: true
+          verbose: true
+          token: ${{ secrets.CODECOV_TOKEN }}
diff --git a/codecov.yml b/codecov.yml
index 9e66d02..24a30db 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -12,6 +12,8 @@ parsers:
     branch_detection:
       conditional: no
       loop: no
+  cobertura:
+    partials_as_hits: true
 ignore:
   - "tests"
   - "benchmark"
diff --git a/tests/poolstl_test.cpp b/tests/poolstl_test.cpp
index 074a7ee..08a1725 100644
--- a/tests/poolstl_test.cpp
+++ b/tests/poolstl_test.cpp
@@ -578,6 +578,7 @@ TEST_CASE("exclusive_scan", "[alg][algorithm]") {
 }
 #endif
 
+#if POOLSTL_HAVE_CXX17_LIB
 TEST_CASE("reduce", "[alg][numeric]") {
     for (auto num_threads : test_thread_counts) {
         ttp::task_thread_pool pool(num_threads);
@@ -585,16 +586,13 @@ TEST_CASE("reduce", "[alg][numeric]") {
         for (auto num_iters : test_arr_sizes) {
             auto v = iota_vector(num_iters);
 
-#if POOLSTL_HAVE_CXX17_LIB
             auto seq = std::reduce(poolstl::par_if(false), v.cbegin(), v.cend());
-#else
-            auto seq = poolstl::internal::cpp17::reduce(v.cbegin(), v.cend());
-#endif
             auto par = std::reduce(poolstl::par.on(pool),  v.cbegin(), v.cend());
             REQUIRE(seq == par);
         }
     }
 }
+#endif
 
 #if POOLSTL_HAVE_CXX17_LIB
 TEST_CASE("transform_reduce_1", "[alg][numeric]") {