diff --git a/.github/workflows/cmake-multi-platform.yml b/.github/workflows/cmake-multi-platform.yml
index 36436e7..a989ffd 100644
--- a/.github/workflows/cmake-multi-platform.yml
+++ b/.github/workflows/cmake-multi-platform.yml
@@ -370,6 +370,8 @@ jobs:
         shell: bash
         run: |
           cmake --preset ${{ matrix.preset }} \
+            -DCMAKE_C_COMPILER=$(xcrun --find clang) \
+            -DCMAKE_CXX_COMPILER=$(xcrun --find clang++) \
             -DOMATH_BUILD_TESTS=ON \
             -DOMATH_BUILD_BENCHMARK=OFF \
             -DOMATH_ENABLE_COVERAGE=${{ matrix.coverage == true && 'ON' || 'OFF' }} \
@@ -389,8 +391,6 @@ jobs:
         shell: bash
         run: |
           brew install lcov
-          # Clean stale profraw files before running coverage
-          find cmake-build/build/${{ matrix.preset }} -name "*.profraw" -delete 2>/dev/null || true
           chmod +x scripts/coverage-llvm.sh
           ./scripts/coverage-llvm.sh \
             "${{ github.workspace }}" \
diff --git a/scripts/coverage-llvm.sh b/scripts/coverage-llvm.sh
index 20a271a..c31a704 100755
--- a/scripts/coverage-llvm.sh
+++ b/scripts/coverage-llvm.sh
@@ -17,8 +17,23 @@ echo "[*] Output dir: ${OUTPUT_DIR}"
 find_llvm_tool() {
     local tool_name="$1"
 
-    # macOS: derive from the same directory as the active clang to guarantee
-    # the profraw format version matches the compiler that instrumented the binary.
+    # First priority: derive from the actual compiler used by cmake (CMakeCache.txt).
+    # This guarantees the profraw format version matches the instrumented binary.
+    local cache_file="${BINARY_DIR}/CMakeCache.txt"
+    if [[ -f "$cache_file" ]]; then
+        local cmake_cxx
+        cmake_cxx=$(grep '^CMAKE_CXX_COMPILER:' "$cache_file" | cut -d= -f2)
+        if [[ -n "$cmake_cxx" && -x "$cmake_cxx" ]]; then
+            local tool_path
+            tool_path="$(dirname "$cmake_cxx")/${tool_name}"
+            if [[ -x "$tool_path" ]]; then
+                echo "$tool_path"
+                return 0
+            fi
+        fi
+    fi
+
+    # macOS: derive from xcrun clang as fallback
     if [[ "$(uname)" == "Darwin" ]]; then
         local clang_path
         clang_path=$(xcrun --find clang 2>/dev/null)
@@ -65,7 +80,13 @@ echo "[*] Using: ${LLVM_COV}"
 
 # Print version info for debugging version mismatches
 if [[ "$(uname)" == "Darwin" ]]; then
-    echo "[*] Compiler: $(xcrun clang --version | head -1)"
+    echo "[*] Default clang: $(xcrun clang --version 2>&1 | head -1)"
+    # Show actual compiler used by the build (from CMakeCache.txt if available)
+    CACHE_FILE="${BINARY_DIR}/CMakeCache.txt"
+    if [[ -f "$CACHE_FILE" ]]; then
+        ACTUAL_CXX=$(grep '^CMAKE_CXX_COMPILER:' "$CACHE_FILE" | cut -d= -f2)
+        echo "[*] Build compiler: ${ACTUAL_CXX} ($(${ACTUAL_CXX} --version 2>&1 | head -1))"
+    fi
     echo "[*] profdata: $(${LLVM_PROFDATA} show --version 2>&1 | head -1 || true)"
 fi