diff --git a/.github/workflows/CI-mingw.yml b/.github/workflows/CI-mingw.yml
deleted file mode 100644
index 390de83d..00000000
--- a/.github/workflows/CI-mingw.yml
+++ /dev/null
@@ -1,141 +0,0 @@
-name: CI-mingw
-
-on: [push, pull_request]
-
-permissions:
-  contents: read
-
-defaults:
-  run:
-    shell: msys2 {0}
-
-jobs:
-  build:
-
-    strategy:
-      matrix:
-        compiler: [g++, clang++]
-        # TODO: add MSYS after #556 is fixed
-        msystem: [MINGW32, MINGW64, CLANG64]
-        include:
-          #- msystem: MSYS
-          #  pkg-prefix: ''
-          - msystem: MINGW32
-            pkg-prefix: 'mingw-w64-i686-'
-          - msystem: MINGW64
-            pkg-prefix: 'mingw-w64-x86_64-'
-          - msystem: CLANG64
-            pkg-prefix: 'mingw-w64-clang-x86_64-'
-          - compiler: g++
-            compiler-pkg: gcc
-          - compiler: clang++
-            compiler-pkg: clang
-        exclude:
-          - msystem: CLANG64
-            compiler: g++
-          # the mingw-w64-i686-clang package is no longer available
-          - msystem: MINGW32
-            compiler: clang++
-      fail-fast: false
-
-    runs-on: windows-2025
-
-    env:
-      CXX: ${{ matrix.compiler }}
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-
-      - name: Set up MSYS2
-        uses: msys2/setup-msys2@v2
-        with:
-          release: false # use pre-installed
-          msystem: ${{ matrix.msystem }}
-          # TODO: install mingw-w64-x86_64-make and use mingw32.make instead - currently fails with "Windows Subsystem for Linux has no installed distributions."
-          # TODO: also run tests with non-prefixed Python?
-          install: >-
-            make
-            ${{ matrix.pkg-prefix }}cmake
-            ${{ matrix.pkg-prefix }}python
-            ${{ matrix.pkg-prefix }}python-pytest
-
-      - name: install compiler
-        run: |
-          pacman -S --noconfirm ${{ matrix.pkg-prefix }}${{ matrix.compiler-pkg }}
-          ${CXX} -v
-
-      - name: make simplecpp
-        run: |
-          make -j$(nproc) CXXOPTS="-Werror"
-
-      # gcc *and* clang are required to run-tests.py
-      # install it at this point since it has gcc as dependency which might interfere with the build
-      - name: install compiler (clang)
-        if: matrix.compiler == 'g++'
-        run: |
-          pacman -S --noconfirm clang
-
-      - name: install compiler (gcc)
-        if: matrix.compiler == 'clang++'
-        run: |
-          pacman -S --noconfirm gcc
-
-      - name: make test
-        run: |
-          # TODO: run tests with Windows paths
-          make -j$(nproc) test
-
-      - name: selfcheck
-        run: |
-          # TODO: run tests with Windows paths
-          make -j$(nproc) selfcheck
-
-      - name: make (c++14)
-        run: |
-          make clean
-          make -j$(nproc) CXXOPTS="-Werror -std=c++14"
-
-      - name: make (c++17)
-        run: |
-          make clean
-          make -j$(nproc) CXXOPTS="-Werror -std=c++17"
-
-      - name: make (c++20)
-        run: |
-          make clean
-          make -j$(nproc) CXXOPTS="-Werror -std=c++20"
-
-      - name: make (c++23)
-        run: |
-          make clean
-          make -j$(nproc) CXXOPTS="-Werror -std=c++23"
-
-      - name: Run CMake
-        run: |
-          cmake -S . -B cmake.output -DCMAKE_COMPILE_WARNING_AS_ERROR=On
-
-      - name: CMake simplecpp
-        run: |
-          cmake --build cmake.output --target simplecpp -- -j $(nproc)
-
-      - name: CMake testrunner
-        run: |
-          cmake --build cmake.output --target testrunner -- -j $(nproc)
-
-      - name: Run testrunner
-        run: |
-          ./cmake.output/testrunner
-
-      - name: Run with libstdc++ debug mode
-        if: matrix.compiler == 'g++'
-        run: |
-          make clean
-          make -j$(nproc) test selfcheck CXXOPTS="-Werror -g3 -D_GLIBCXX_DEBUG"
-
-      - name: Run with libc++ hardening mode
-        if: matrix.compiler == 'clang++' && matrix.msystem == 'CLANG64'
-        run: |
-          make clean
-          make -j$(nproc) test selfcheck CXXOPTS="-Werror -stdlib=libc++ -g3 -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_DEBUG" LDOPTS="-lc++"
diff --git a/.github/workflows/CI-unixish.yml b/.github/workflows/CI-unixish.yml
deleted file mode 100644
index 1a4ce649..00000000
--- a/.github/workflows/CI-unixish.yml
+++ /dev/null
@@ -1,194 +0,0 @@
-name: CI-unixish
-
-on: [push, pull_request]
-
-permissions:
-  contents: read
-
-jobs:
-  build:
-
-    strategy:
-      matrix:
-        os: [ubuntu-22.04, ubuntu-22.04-arm, ubuntu-24.04, ubuntu-24.04-arm, macos-14, macos-15, macos-15-intel, macos-26, macos-26-intel]
-        compiler: [clang++]
-        include:
-          - os: ubuntu-22.04
-            compiler: g++
-          - os: ubuntu-24.04
-            compiler: g++
-      fail-fast: false
-
-    runs-on: ${{ matrix.os }}
-
-    env:
-      CXX: ${{ matrix.compiler }}
-
-    steps:
-    - uses: actions/checkout@v6
-      with:
-        persist-credentials: false
-
-    # the man-db trigger causes package installations to stall for several minutes at times. so just drop the package.
-    # see https://github.com/actions/runner/issues/4030
-    - name: Remove man-db package on ubuntu
-      if: matrix.os == 'ubuntu-24.04'
-      run: |
-        sudo apt-get update
-        sudo apt-get remove man-db
-
-    - name: Install missing software on ubuntu
-      if: matrix.os == 'ubuntu-24.04'
-      run: |
-          sudo apt-get update
-          sudo apt-get install valgrind
-
-    # llvm contains llvm-profdata
-    - name: Install missing software on ubuntu (clang++)
-      if: contains(matrix.os, 'ubuntu') && matrix.compiler == 'clang++'
-      run: |
-        sudo apt-get update
-        sudo apt-get install libc++-dev llvm
-
-      # coreutils contains "nproc"
-    - name: Install missing software on macos
-      if: contains(matrix.os, 'macos')
-      run: |
-        brew install coreutils
-
-    - name: Install missing Python packages
-      run: |
-        python3 -m pip config set global.break-system-packages true
-        python3 -m pip install pytest
-
-    - name: make simplecpp
-      run: make -j$(nproc) CXXOPTS="-Werror"
-
-    - name: make test
-      run: make -j$(nproc) test CXXOPTS="-Werror"
-
-    - name: selfcheck
-      run: |
-        make -j$(nproc) selfcheck
-
-    - name: make (c++14)
-      run: |
-        make clean
-        make -j$(nproc) CXXOPTS="-Werror -std=c++14"
-
-    - name: make (c++17)
-      run: |
-        make clean
-        make -j$(nproc) CXXOPTS="-Werror -std=c++17"
-
-    - name: make (c++20)
-      run: |
-        make clean
-        make -j$(nproc) CXXOPTS="-Werror -std=c++20"
-
-    - name: make (c++23)
-      run: |
-        make clean
-        # ubuntu-22.04 and macos-14 do not support c++23 yet
-        make -j$(nproc) CXXOPTS="-Werror -std=c++2b"
-
-    - name: Run CMake
-      run: |
-        cmake -S . -B cmake.output -Werror=dev --warn-uninitialized -DCMAKE_COMPILE_WARNING_AS_ERROR=On
-
-    - name: CMake simplecpp
-      run: |
-        cmake --build cmake.output --target simplecpp -- -j $(nproc)
-
-    - name: CMake testrunner
-      run: |
-        cmake --build cmake.output --target testrunner -- -j $(nproc)
-        ./cmake.output/testrunner
-        # Re-run tests from within the build directory to validate that
-        # SIMPLECPP_TEST_SOURCE_DIR is correctly defined and resolved
-        (cd cmake.output && ./testrunner)
-
-    - name: Run valgrind
-      if: matrix.os == 'ubuntu-24.04'
-      run: |
-          make clean
-          make -j$(nproc) CXXOPTS="-O1"
-          valgrind --leak-check=full --num-callers=50 --show-reachable=yes --track-origins=yes --gen-suppressions=all --error-exitcode=42 ./testrunner
-          # TODO: run Python tests with valgrind
-          VALGRIND_TOOL=memcheck ./selfcheck.sh
-
-    - name: Run with libstdc++ debug mode
-      if: matrix.os == 'ubuntu-24.04' && matrix.compiler == 'g++'
-      run: |
-        make clean
-        make -j$(nproc) test selfcheck CXXOPTS="-Werror -g3 -D_GLIBCXX_DEBUG"
-
-    - name: Run with libc++ hardening mode
-      if: matrix.os == 'ubuntu-24.04' && matrix.compiler == 'clang++'
-      run: |
-        make clean
-        make -j$(nproc) test selfcheck CXXOPTS="-Werror -stdlib=libc++ -g3 -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_DEBUG" LDOPTS="-lc++"
-
-    - name: Run AddressSanitizer
-      if: matrix.os == 'ubuntu-24.04' || matrix.os == 'macos-26'
-      run: |
-        make clean
-        make -j$(nproc) test selfcheck CXXOPTS="-Werror -O2 -g3 -fsanitize=address" LDOPTS="-fsanitize=address"
-      env:
-        ASAN_OPTIONS: detect_stack_use_after_return=1
-
-    - name: Run UndefinedBehaviorSanitizer
-      if: matrix.os == 'ubuntu-24.04' || matrix.os == 'macos-26'
-      run: |
-        make clean
-        make -j$(nproc) test selfcheck CXXOPTS="-Werror -O2 -g3 -fsanitize=undefined -fno-sanitize=signed-integer-overflow" LDOPTS="-fsanitize=undefined -fno-sanitize=signed-integer-overflow"
-      env:
-        UBSAN_OPTIONS: print_stacktrace=1:halt_on_error=1:report_error_type=1
-
-    # TODO: requires instrumented libc++
-    - name: Run MemorySanitizer
-      if: false && matrix.os == 'ubuntu-24.04' && matrix.compiler == 'clang++'
-      run: |
-        make clean
-        make -j$(nproc) test selfcheck CXXOPTS="-Werror -O2 -g3 -stdlib=libc++ -fsanitize=memory" LDOPTS="-lc++ -fsanitize=memory"
-
-    - name: Run callgrind
-      if: matrix.os == 'ubuntu-24.04'
-      run: |
-        wget https://github.com/danmar/simplecpp/archive/refs/tags/1.5.1.tar.gz
-        tar xvf 1.5.1.tar.gz
-        rm -f 1.5.1.tar.gz
-        
-        make clean
-        make -j$(nproc) CXXOPTS="-O2 -g3" simplecpp
-        VALGRIND_TOOL=callgrind SIMPLECPP_PATH=simplecpp-1.5.1 ./selfcheck.sh >callgrind.log || (cat callgrind.log && false)
-        cat callgrind.log
-        
-        # PGO - start
-        make clean
-        make -j$(nproc) CXXOPTS="-O2 -g3 -fprofile-generate" LDOPTS="-fprofile-generate" simplecpp
-        SIMPLECPP_PATH=simplecpp-1.5.1 ./selfcheck.sh >/dev/null
-        
-        if compgen -G "default_*.profraw" > /dev/null; then
-          llvm-profdata merge -output=default.profdata default_*.profraw
-        fi
-        
-        make clean
-        make -j$(nproc) CXXOPTS="-O2 -g3 -fprofile-use" LDOPTS="-fprofile-use" simplecpp
-        VALGRIND_TOOL=callgrind SIMPLECPP_PATH=simplecpp-1.5.1 ./selfcheck.sh >callgrind_pgo.log || (cat callgrind_pgo.log && false)
-        cat callgrind_pgo.log
-        # PGO - end
-        
-        for f in callgrind.out.*;
-        do
-          callgrind_annotate --auto=no $f > $f.annotated.log
-          head -50 $f.annotated.log
-        done
-        rm -rf simplecpp-1.5.1
-
-    - uses: actions/upload-artifact@v4
-      if: matrix.os == 'ubuntu-24.04'
-      with:
-        name: Callgrind Output - ${{ matrix.compiler }}
-        path: |
-          ./callgrind.*
diff --git a/.github/workflows/CI-windows.yml b/.github/workflows/CI-windows.yml
deleted file mode 100644
index cfced0d2..00000000
--- a/.github/workflows/CI-windows.yml
+++ /dev/null
@@ -1,82 +0,0 @@
-# Some convenient links:
-# - https://github.com/actions/virtual-environments/blob/master/images/win/Windows2019-Readme.md
-#
-
-name: CI-windows
-
-on: [push,pull_request]
-
-permissions:
-  contents: read
-
-defaults:
-  run:
-    shell: cmd
-    
-jobs:
-
-  build:
-    strategy:
-      matrix:
-        os: [windows-2022, windows-2025, windows-11-arm]
-        config: [Release, Debug]
-      fail-fast: false
-
-    runs-on: ${{ matrix.os }}
-
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Setup msbuild.exe
-        uses: microsoft/setup-msbuild@v2
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: '3.14'
-          check-latest: true
-
-      - name: Install missing Python packages
-        run: |
-          python -m pip install pip --upgrade || exit /b !errorlevel!
-          python -m pip install pytest || exit /b !errorlevel!
-
-      - name: Run CMake
-        run: |
-          cmake -G "Visual Studio 17 2022" -A x64 -Werror=dev --warn-uninitialized -DCMAKE_COMPILE_WARNING_AS_ERROR=On . || exit /b !errorlevel!
-
-      - name: Build
-        run: |
-           msbuild -m simplecpp.sln /p:Configuration=${{ matrix.config }} /p:Platform=x64 || exit /b !errorlevel!
-           
-      - name: Test
-        run: |
-          .\${{ matrix.config }}\testrunner.exe || exit /b !errorlevel!
-
-      - name: Selfcheck
-        run: |
-          .\${{ matrix.config }}\simplecpp.exe simplecpp.cpp -e || exit /b !errorlevel!
-
-      - name: integration test
-        run: |
-          set SIMPLECPP_EXE_PATH=.\${{ matrix.config }}\simplecpp.exe
-          python -m pytest integration_test.py -vv || exit /b !errorlevel!
-
-      - name: Run CMake (c++17)
-        run: |
-          cmake -S . -B build.cxx17 -G "Visual Studio 17 2022" -A x64 -Werror=dev --warn-uninitialized -DCMAKE_CXX_STANDARD=17 -DCMAKE_COMPILE_WARNING_AS_ERROR=On || exit /b !errorlevel!
-
-      - name: Build (c++17)
-        run: |
-          msbuild -m build.cxx17\simplecpp.sln /p:Configuration=${{ matrix.config }} /p:Platform=x64 || exit /b !errorlevel!
-
-      - name: Run CMake (c++20)
-        run: |
-          cmake -S . -B build.cxx20 -G "Visual Studio 17 2022" -A x64 -Werror=dev --warn-uninitialized -DCMAKE_CXX_STANDARD=20 -DCMAKE_COMPILE_WARNING_AS_ERROR=On || exit /b !errorlevel!
-
-      - name: Build (c++20)
-        run: |
-          msbuild -m build.cxx20\simplecpp.sln /p:Configuration=${{ matrix.config }} /p:Platform=x64 || exit /b !errorlevel!
-    
diff --git a/.github/workflows/clang-tidy.yml b/.github/workflows/clang-tidy.yml
deleted file mode 100644
index 333672d7..00000000
--- a/.github/workflows/clang-tidy.yml
+++ /dev/null
@@ -1,51 +0,0 @@
-# Syntax reference https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions
-# Environment reference https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners
-name: clang-tidy
-
-on: [push, pull_request]
-
-permissions:
-  contents: read
-
-jobs:
-  build:
-
-    runs-on: ubuntu-24.04
-
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      # the man-db trigger causes package installations to stall for several minutes at times. so just drop the package.
-      # see https://github.com/actions/runner/issues/4030
-      - name: Remove man-db package
-        run: |
-          sudo apt-get update
-          sudo apt-get remove man-db
-
-      - name: Install missing software
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y cmake make
-
-      - name: Install clang
-        run: |
-          wget https://apt.llvm.org/llvm.sh
-          chmod +x llvm.sh
-          sudo ./llvm.sh 22
-          sudo apt-get install clang-tidy-22
-
-      - name: Verify clang-tidy configuration
-        run: |
-          clang-tidy-22 --verify-config
-
-      - name: Prepare CMake
-        run: |
-          cmake -S . -B cmake.output -Werror=dev --warn-uninitialized -DCMAKE_CXX_STANDARD=23 -DCMAKE_COMPILE_WARNING_AS_ERROR=On -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-        env:
-          CXX: clang-22
-
-      - name: Clang-Tidy
-        run: |
-          run-clang-tidy-22 -q -j $(nproc) -enable-check-profile -p=cmake.output
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
deleted file mode 100644
index e9f1361d..00000000
--- a/.github/workflows/format.yml
+++ /dev/null
@@ -1,62 +0,0 @@
-# Syntax reference https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions
-# Environment reference https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners
-name: format
-
-on:
-  push:
-    branches:
-      - 'master'
-      - 'releases/**'
-      - '1.*'
-    tags:
-      - '1.*'
-  pull_request:
-
-permissions:
-  contents: read
-
-jobs:
-  format:
-
-    runs-on: ubuntu-22.04
-
-    defaults:
-      run:
-        shell: bash -euo pipefail {0}
-
-    env:
-      UNCRUSTIFY_INSTALL_DIR: ${{ github.workspace }}/runformat-uncrustify
-
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Determine uncrustify version
-        id: get-uncrustify-version
-        run: |
-          version="$(./runformat --expected-uncrustify-version)"
-          echo "Expected uncrustify version: $version"
-          echo "version=$version" >> "$GITHUB_OUTPUT"
-
-      - name: Set UNCRUSTIFY_VERSION env variable
-        run: |
-          version=$(./runformat --expected-uncrustify-version)
-          echo "version [$version]"
-          echo "UNCRUSTIFY_VERSION=${version}" >> "$GITHUB_ENV"
-
-      - name: Cache uncrustify
-        uses: actions/cache@v4
-        id: cache-uncrustify
-        with:
-          path: ${{ env.UNCRUSTIFY_INSTALL_DIR }}
-          key: ${{ runner.os }}-uncrustify-${{ steps.get-uncrustify-version.outputs.version }}
-
-      - name: Install uncrustify
-        if: steps.cache-uncrustify.outputs.cache-hit != 'true'
-        run: |
-          ./runformat --install --install-dir "${UNCRUSTIFY_INSTALL_DIR}"
-
-      - name: Uncrustify check
-        run: |
-          ./runformat
diff --git a/.github/workflows/fuzz.yml b/.github/workflows/fuzz.yml
new file mode 100644
index 00000000..5bead117
--- /dev/null
+++ b/.github/workflows/fuzz.yml
@@ -0,0 +1,82 @@
+# Syntax reference https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions
+# Environment reference https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners
+name: fuzz
+on: [pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  fuzz:
+    runs-on: ubuntu-24.04
+    if: ${{ github.repository_owner == 'danmar' }}
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      # the man-db trigger causes package installations to stall for several minutes at times. so just drop the package.
+      # see https://github.com/actions/runner/issues/4030
+      - name: Remove man-db package
+        run: |
+          sudo apt-get update
+          sudo apt-get remove man-db
+
+      - name: Install missing software
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y make
+
+      - name: Install clang
+        run: |
+          wget https://apt.llvm.org/llvm.sh
+          chmod +x llvm.sh
+          sudo ./llvm.sh 22
+
+      - name: Generate corpus
+        run: |
+          mkdir corpus_test
+          make testrunner CXXOPTS="-DSTORE_INPUT_DIR=\"\\\"$(pwd)/corpus_test\\\"\""
+          ./testrunner
+
+      - name: Upload corpus (testrunner)
+        uses: actions/upload-artifact@v6
+        with:
+          name: corpus_test
+          path: ./corpus_test
+
+      - name: Build fuzzer
+        id: build
+        run: |
+          make clean
+          # TODO: test O/LTO for best speed
+          # TODO: use -stdlib=libc++ -lc++
+          make -j$(nproc) CXXOPTS="-O3 -flto -fno-omit-frame-pointer -g -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address,undefined -fsanitize-address-use-after-scope -fno-sanitize=integer -fno-sanitize-recover=undefined" LDOPTS="-flto" LIB_FUZZING_ENGINE="-fsanitize=fuzzer" fuzz
+        env:
+          CXX: clang++-22
+
+      - name: Run fuzzer
+        run: |
+          mkdir corpus
+          mkdir artifacts
+          ./fuzz -only_ascii=1 -timeout=5 -fork=$(nproc) -use_value_profile=1 -reduce_inputs=0 -timeout_exitcode=0 -max_total_time=60 -artifact_prefix=./artifacts/ corpus corpus_test
+          # if a crash happens with a file from the corpus the fuzzer will not fail - so fail if any artifacts have been written
+          test $(find ./artifacts -type f | wc -l) -eq 0
+        env:
+          ASAN_OPTIONS: detect_stack_use_after_return=1
+          UBSAN_OPTIONS: print_stacktrace=1:halt_on_error=1:report_error_type=1
+
+      - name: Upload corpus
+        if: success() || failure()
+        uses: actions/upload-artifact@v6
+        with:
+          name: corpus
+          path: ./corpus
+
+      - name: Upload artifacts
+        if: success() || failure()
+        uses: actions/upload-artifact@v6
+        with:
+          name: artifacts
+          path: ./artifacts
diff --git a/Makefile b/Makefile
index b7b54597..5488bfb4 100644
--- a/Makefile
+++ b/Makefile
@@ -12,21 +12,32 @@ test.o: CPPFLAGS += $(TEST_CPPFLAGS)
 test.o: CXXFLAGS += -Wno-multichar
 
 %.o: %.cpp	simplecpp.h
-	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $<
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $< $(LIB_FUZZING_ENGINE)
+
+fuzz_no.o: fuzz.cpp
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -DNO_FUZZ -c -o $@ $^
 
 testrunner:	test.o	simplecpp.o
-	$(CXX) $(LDFLAGS) simplecpp.o test.o -o testrunner
+	$(CXX) $(LDFLAGS) -o $@ $^
 
 test:	testrunner	simplecpp
 	./testrunner
 	python3 run-tests.py
 	python3 -m pytest integration_test.py -vv
 
+fuzz:	fuzz.o simplecpp.o
+	# TODO: use -stdlib=libc++ -lc++
+	# make fuzz CXX=clang++ CXXOPTS="-O2 -fno-omit-frame-pointer -g -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address,undefined -fsanitize-address-use-after-scope -fno-sanitize=integer -fno-sanitize-recover=undefined" LIB_FUZZING_ENGINE="-fsanitize=fuzzer"
+	$(CXX) $(LDFLAGS) $(CXXFLAGS) -o $@ $^ $(LIB_FUZZING_ENGINE)
+
+no-fuzz:	fuzz_no.o simplecpp.o
+	$(CXX) $(LDFLAGS) $(CXXFLAGS) -o $@ $^
+
 selfcheck:	simplecpp
 	CXX=$(CXX) ./selfcheck.sh
 
 simplecpp:	main.o simplecpp.o
-	$(CXX) $(LDFLAGS) main.o simplecpp.o -o simplecpp
+	$(CXX) $(LDFLAGS) -o $@ $^
 
 clean:
-	rm -f testrunner simplecpp *.o
+	rm -f testrunner fuzz no-fuzz simplecpp *.o
diff --git a/fuzz.cpp b/fuzz.cpp
new file mode 100644
index 00000000..88b69e3e
--- /dev/null
+++ b/fuzz.cpp
@@ -0,0 +1,70 @@
+/*
+ * simplecpp - A simple and high-fidelity C/C++ preprocessor library
+ * Copyright (C) 2016-2024 simplecpp team
+ */
+
+#include "simplecpp.h"
+
+#include <cstdint>
+
+#ifdef NO_FUZZ
+#include <cstdlib>
+#include <fstream>
+#include <sstream>
+#include <string>
+#endif
+
+/*
+  0 - store in corpus
+ -1 - omit from corpus
+*/
+static int doProcess(const uint8_t *data, size_t dataSize)
+{
+    simplecpp::OutputList outputList;
+    std::vector<std::string> files;
+    simplecpp::TokenList rawtokens(data, dataSize, files, "test.cpp", &outputList);
+
+    simplecpp::TokenList outputTokens(files);
+    simplecpp::FileDataCache filedata;
+    const simplecpp::DUI dui;
+    std::list<simplecpp::MacroUsage> macroUsage;
+    std::list<simplecpp::IfCond> ifCond;
+    simplecpp::preprocess(outputTokens, rawtokens, files, filedata, dui, &outputList, &macroUsage, &ifCond);
+
+    simplecpp::cleanup(filedata);
+
+    return 0;
+}
+
+#ifndef NO_FUZZ
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataSize);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataSize)
+{
+    return doProcess(data, dataSize);
+}
+#else
+int main(int argc, char * argv[])
+{
+    if (argc < 2 || argc > 3)
+        return EXIT_FAILURE;
+
+    std::ifstream f(argv[1]);
+    if (!f.is_open())
+        return EXIT_FAILURE;
+
+    std::ostringstream oss;
+    oss << f.rdbuf();
+
+    if (!f.good())
+        return EXIT_FAILURE;
+
+    const int cnt = (argc == 3) ? std::stoi(argv[2]) : 1;
+
+    const std::string code = oss.str();
+    for (int i = 0; i < cnt; ++i)
+        doProcess(reinterpret_cast<const uint8_t*>(code.data()), code.size());
+
+    return EXIT_SUCCESS;
+}
+#endif
diff --git a/simplecpp.cpp b/simplecpp.cpp
index a0e8caa8..89bb7420 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -53,8 +53,10 @@
 
 #ifdef _WIN32
 #  include <direct.h>
+using mode_t = unsigned short;
 #else
 #  include <sys/stat.h>
+#  include <sys/types.h>
 #endif
 
 static bool isHex(const std::string &s)
@@ -3044,9 +3046,11 @@ static std::string openHeaderDirect(std::ifstream &f, const std::string &path)
     if (nonExistingFilesCache.contains(path))
         return "";  // file is known not to exist, skip expensive file open call
 #endif
-    f.open(path.c_str());
-    if (f.is_open())
-        return path;
+    if (simplecpp::isFile(path)) {
+        f.open(path.c_str());
+        if (f.is_open())
+            return path;
+    }
 #ifdef SIMPLECPP_WINDOWS
     nonExistingFilesCache.add(path);
 #endif
@@ -3180,6 +3184,9 @@ bool simplecpp::FileDataCache::getFileId(const std::string &path, FileID &id)
     if (stat(path.c_str(), &statbuf) != 0)
         return false;
 
+    if ((statbuf.st_mode & S_IFMT) != S_IFREG)
+        return false;
+
     id.dev = statbuf.st_dev;
     id.ino = statbuf.st_ino;
 
@@ -3967,3 +3974,21 @@ std::string simplecpp::getCppStdString(const std::string &std)
 {
     return getCppStdString(getCppStd(std));
 }
+
+static mode_t file_type(const std::string &path)
+{
+    struct stat file_stat;
+    if (stat(path.c_str(), &file_stat) == -1)
+        return 0;
+    return file_stat.st_mode & S_IFMT;
+}
+
+bool simplecpp::isFile(const std::string &path)
+{
+    return file_type(path) == S_IFREG;
+}
+
+bool simplecpp::isDirectory(const std::string &path)
+{
+    return file_type(path) == S_IFDIR;
+}
diff --git a/simplecpp.h b/simplecpp.h
index b744e62d..4758ee93 100644
--- a/simplecpp.h
+++ b/simplecpp.h
@@ -443,6 +443,20 @@ namespace simplecpp {
         bool removeComments{}; /** remove comment tokens from included files */
     };
 
+    /**
+     * @brief Checks if given path is a file
+     * @param path Path to be checked
+     * @return true if given path is a file
+     */
+    SIMPLECPP_LIB bool isFile(const std::string &path);
+
+    /**
+     * @brief Checks if a given path is a directory
+     * @param path Path to be checked
+     * @return true if given path is a directory
+     */
+    SIMPLECPP_LIB bool isDirectory(const std::string &path);
+
     struct SIMPLECPP_LIB FileData {
         /** The canonical filename associated with this data */
         std::string filename;
diff --git a/test.cpp b/test.cpp
index bc8cb4d5..74fc7ad3 100644
--- a/test.cpp
+++ b/test.cpp
@@ -81,9 +81,28 @@ static void testcase(const std::string &name, void (*f)(), int argc, char * cons
 
 #define TEST_CASE(F)    (testcase(#F, F, argc, argv))
 
+#ifdef STORE_INPUT_DIR
+// make testrunner CXXOPTS="-DSTORE_INPUT_DIR=\"\\\"/home/user/simple_corpus\\\"\""
+#include <atomic>
+#include <fstream>
+
+static void storeInput(const std::string& str)
+{
+    static std::atomic_uint64_t num(0);
+    {
+        std::ofstream out(STORE_INPUT_DIR "/" + std::to_string(num++));
+        out << str;
+    }
+}
+#endif
+
 static simplecpp::TokenList makeTokenList(const char code[], std::size_t size, std::vector<std::string> &filenames, const std::string &filename=std::string(), simplecpp::OutputList *outputList=nullptr)
 {
-    std::istringstream istr(std::string(code, size));
+    const std::string str(code, size);
+#ifdef STORE_INPUT_DIR
+    storeInput(str);
+#endif
+    std::istringstream istr(str);
     return {istr,filenames,filename,outputList};
 }
 
@@ -691,6 +710,181 @@ static void define13()
                   "}", preprocess(code));
 }
 
+static void define14() // #296
+{
+    const char code[] = "#define bar(x) x % 2\n"
+                        "#define foo(x) printf(#x \"\\n\")\n"
+                        "\n"
+                        " foo(bar(3));\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "printf ( \"bar(3)\" \"\\n\" ) ;", preprocess(code));
+}
+
+static void define15() // #231
+{
+    const char code[] = "#define CAT(a, b) CAT2(a, b)\n"
+                        "#define CAT2(a, b) a ## b\n"
+                        "#define FOO x\n"
+                        "#define BAR() CAT(F, OO)\n"
+                        "#define BAZ CAT(B, AR)()\n"
+                        "BAZ\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "x", preprocess(code));
+}
+
+static void define16() // #201
+{
+    const char code[] = "#define ALL_COLORS(warm_colors) \\\n"
+                        "  X(Blue) \\\n"
+                        "  X(Green) \\\n"
+                        "  X(Purple) \\\n"
+                        "  warm_colors\n"
+                        "\n"
+                        "#define WARM_COLORS \\\n"
+                        "  X(Red) \\\n"
+                        "  X(Yellow) \\\n"
+                        "  X(Orange)\n"
+                        "\n"
+                        "#define COLOR_SET ALL_COLORS(WARM_COLORS)\n"
+                        "\n"
+                        "#define X(color) #color,\n"
+                        "\n"
+                        "COLOR_SET\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\"Blue\" , \"Green\" , \"Purple\" , \"Red\" , \"Yellow\" , \"Orange\" ,", preprocess(code));
+}
+
+static void define17() // #185
+{
+    const char code[] = "#define at(x, y) x##y\n"
+                        "#define b(...) \\\n"
+                        "aa(__VA_ARGS__, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , \\\n"
+                        ", , , , , , , , 2)\n"
+                        "#define aa(c, d, a, b, e, f, g, h, ab, ac, i, ad, j, k, l, m, n, o, p, ae, q, \\\n"
+                        "r, s, t, u, v, w, x, y, z, af, ag, ah, ai, aj, ak, al, am, an, ao, \\\n"
+                        "ap) \\\n"
+                        "ap\n"
+                        "#define aq(...) ar(b(__VA_ARGS__), __VA_ARGS__) static_assert(true, \" \")\n"
+                        "#define ar(ap, ...) at(I_, ap)(__VA_ARGS__)\n"
+                        "#define I_2(as, a)\n"
+                        "aq(a, array);\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "static_assert ( true , \" \" ) ;", preprocess(code));
+}
+
+static void define18() // #130
+{
+    const char code[] = "#define MAC2STR(x) x[0],x[1],x[2],x[3],x[4],x[5]\n"
+                        "#define FT_DEBUG(fmt, args...) if(pGlobalCtx && pGlobalCtx->debug_level>=2) printf(\"FT-dbg: \"fmt, ##args)\n"
+                        "\n"
+                        "FT_DEBUG(\"  %02x:%02x:%02x:%02x:%02x:%02x\\n\", MAC2STR(pCtx->wlan_intf_addr[i]));\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "if ( pGlobalCtx && pGlobalCtx -> debug_level >= 2 ) printf ( \"FT-dbg: \" \"  %02x:%02x:%02x:%02x:%02x:%02x\\n\" , pCtx -> wlan_intf_addr [ i ] [ 0 ] , pCtx -> wlan_intf_addr [ i ] [ 1 ] , pCtx -> wlan_intf_addr [ i ] [ 2 ] , pCtx -> wlan_intf_addr [ i ] [ 3 ] , pCtx -> wlan_intf_addr [ i ] [ 4 ] , pCtx -> wlan_intf_addr [ i ] [ 5 ] ) ;", preprocess(code));
+}
+
+static void define19() // #124
+{
+    const char code[] = "#define CONCAT(tok) tok##suffix\n"
+                        "\n"
+                        "CONCAT(Test);\n"
+                        "CONCAT(const Test);\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "Testsuffix ;\n"
+                  "const Testsuffix ;", preprocess(code));
+}
+
+static void define20() // #113
+{
+    const char code[] = "#define TARGS4 T1,T2,T3,T4\n"
+                        "#define FOOIMPL(T__CLASS, TARGS) void foo(const T__CLASS<TARGS>& x) { }\n"
+                        "#define FOOIMPL_4(T__CLASS)      FOOIMPL(T__CLASS, TARGS4)\n"
+                        "FOOIMPL_4(y)\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "void foo ( const y < T1 , T2 , T3 , T4 > & x ) { }", preprocess(code));
+}
+
+static void define21() // #66
+{
+    const char code[] = "#define GETMYID(a) ((a))+1\n"
+                        "#define FIGHT_FOO(c, ...) foo(c, ##__VA_ARGS__)\n"
+                        "FIGHT_FOO(1, GETMYID(a));\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "foo ( 1 , ( ( a ) ) + 1 ) ;", preprocess(code));
+}
+
+static void define22() // #40
+{
+    const char code[] = "#define COUNTER_NAME(NAME, ...) NAME##Count\n"
+                        "#define COMMA ,\n"
+                        "\n"
+                        "#define DECLARE_COUNTERS(LIST) unsigned long LIST(COUNTER_NAME, COMMA);\n"
+                        "\n"
+                        "#define ACTUAL_LIST(FUNCTION, SEPARATOR) \\\n"
+                        "FUNCTION(event1, int, foo) SEPARATOR \\\n"
+                        "FUNCTION(event2, char, bar)\n"
+                        "\n"
+                        "DECLARE_COUNTERS(ACTUAL_LIST)\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "unsigned long event1Count , event2Count ;", preprocess(code));
+}
+
+static void define23() // #40
+{
+    const char code[] = "#define COMMA ,\n"
+                        "#define MULTI(SEPARATOR) A SEPARATOR B\n"
+                        "\n"
+                        "#define VARS MULTI(COMMA)\n"
+                        "unsigned VARS;\n";
+    ASSERT_EQUALS("\n"
+                  "\n"
+                  "\n"
+                  "\n"
+                  "unsigned A , B ;", preprocess(code));
+}
 
 
 static void define_invalid_1()
@@ -1153,6 +1347,15 @@ static void pragma_backslash()
     ASSERT_EQUALS("", preprocess(code, &outputList));
 }
 
+static void pragma_backslash_2() // #217
+{
+    const char code[] = "#pragma comment(linker, \"foo \\\n"
+                        "bar\")\n";
+
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess(code, &outputList));
+}
+
 static void dollar()
 {
     ASSERT_EQUALS("$ab", readfile("$ab"));
@@ -2247,6 +2450,44 @@ static void missingHeader4()
     ASSERT_EQUALS("file0,1,syntax_error,No header in #include\n", toString(outputList));
 }
 
+#ifndef _WIN32
+static void missingHeader5()
+{
+    // this is a directory
+    const char code[] = "#include \"/\"\n";
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess(code, &outputList));
+    ASSERT_EQUALS("file0,1,missing_header,Header not found: \"/\"\n", toString(outputList));
+}
+
+static void missingHeader6()
+{
+    // this is a directory
+    const char code[] = "#include \"/usr\"\n";
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess(code, &outputList));
+    ASSERT_EQUALS("file0,1,missing_header,Header not found: \"/usr\"\n", toString(outputList));
+}
+
+static void missingHeader7()
+{
+    // this is a directory
+    const char code[] = "#include </>\n";
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess(code, &outputList));
+    ASSERT_EQUALS("file0,1,missing_header,Header not found: </>\n", toString(outputList));
+}
+
+static void missingHeader8()
+{
+    // this is a directory
+    const char code[] = "#include </usr>\n";
+    simplecpp::OutputList outputList;
+    ASSERT_EQUALS("", preprocess(code, &outputList));
+    ASSERT_EQUALS("file0,1,missing_header,Header not found: </usr>\n", toString(outputList));
+}
+#endif
+
 static void nestedInclude()
 {
     const char code[] = "#include \"test.h\"\n";
@@ -3617,6 +3858,14 @@ static void leak()
                             "#define e\n";
         (void)preprocess(code, simplecpp::DUI());
     }
+    {
+        const char code[] = "#include</\\\\>\n"
+                            "#include</\\\\>\n";
+        simplecpp::OutputList outputList;
+        ASSERT_EQUALS("", preprocess(code, &outputList));
+        ASSERT_EQUALS("file0,1,missing_header,Header not found: </\\\\>\n"
+                      "file0,2,missing_header,Header not found: </\\\\>\n", toString(outputList));
+    }
 }
 
 int main(int argc, char **argv)
@@ -3655,6 +3904,16 @@ int main(int argc, char **argv)
     TEST_CASE(define11);
     TEST_CASE(define12);
     TEST_CASE(define13);
+    TEST_CASE(define14); // #296
+    TEST_CASE(define15); // #231
+    TEST_CASE(define16); // #201
+    TEST_CASE(define17); // #185
+    TEST_CASE(define18); // #130
+    TEST_CASE(define19); // #124
+    TEST_CASE(define20); // #113
+    TEST_CASE(define21); // #66
+    TEST_CASE(define22); // #40
+    TEST_CASE(define23); // #40
     TEST_CASE(define_invalid_1);
     TEST_CASE(define_invalid_2);
     TEST_CASE(define_define_1);
@@ -3697,6 +3956,7 @@ int main(int argc, char **argv)
     TEST_CASE(define_va_opt_9); // #632
 
     TEST_CASE(pragma_backslash); // multiline pragma directive
+    TEST_CASE(pragma_backslash_2); // #217
 
     // UB: #ifdef as macro parameter
     TEST_CASE(define_ifdef);
@@ -3801,6 +4061,12 @@ int main(int argc, char **argv)
     TEST_CASE(missingHeader2);
     TEST_CASE(missingHeader3);
     TEST_CASE(missingHeader4);
+#ifndef _WIN32
+    TEST_CASE(missingHeader5);
+    TEST_CASE(missingHeader6);
+    TEST_CASE(missingHeader7);
+    TEST_CASE(missingHeader8);
+#endif
     TEST_CASE(nestedInclude);
     TEST_CASE(systemInclude);
     TEST_CASE(circularInclude);