diff --git a/GNUmakefile b/GNUmakefile
index 883c975..02bdd93 100755
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -3,73 +3,78 @@
 #XXX GENERATOR?="Unix Makefiles"
 GENERATOR?=Ninja
 
-STAGEDIR?="${CURDIR}/stage"
-CMAKE_PRESET:=-G "${GENERATOR}" -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DCMAKE_BUILD_TYPE=Debug -DCMAKE_PREFIX_PATH=${STAGEDIR}
-
+STAGE_DIR?=$(CURDIR)/stage
+BUILD_TYPE?=Debug
+CMAKE_PRESET:=-G "$(GENERATOR)" -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DCMAKE_BUILD_TYPE=$(BUILD_TYPE)
+-DCMAKE_PREFIX_PATH=$(STAGE_DIR)
+# Note: not needed -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
 
 #XXX export CXX=clang++
 export CPM_USE_LOCAL_PACKAGES=0
 export CPM_SOURCE_CACHE=${HOME}/.cache/CPM
 
+PROJECT_NAME:=$(shell basename $(CURDIR))
+BUILD_DIR?=../build-$(PROJECT_NAME)-$(CXX)-$(BUILD_TYPE)
+
 .PHONY: update format all test standalone doc check clean distclean lock
 
 # the default target does just all, but neither standalone nor doc
 test:
 
 clean:
-	find . -type d -name build | xargs rm -rf
+	rm -rf $(BUILD_DIR) build-*
 
 distclean: clean
-	rm -rf build ${STAGEDIR}
+	rm -rf $(STAGE_DIR)
 
 # update CPM.cmake
 update:
 	wget -q -O cmake/CPM.cmake https://github.com/cpm-cmake/CPM.cmake/releases/latest/download/get_cpm.cmake
 
 lock: all standalone doc
-	cmake --build build/all --target cpm-update-package-lock
-	cmake --build build/test --target cpm-update-package-lock
-	cmake --build build/install --target cpm-update-package-lock
-	cmake --build build/standalone --target cpm-update-package-lock
-	cmake --build build/documentation --target cpm-update-package-lock
+	cmake --build $(BUILD_DIR)/all --target cpm-update-package-lock
+	cmake --build $(BUILD_DIR)/test --target cpm-update-package-lock
+	cmake --build $(BUILD_DIR)/install --target cpm-update-package-lock
+	cmake --build $(BUILD_DIR)/standalone --target cpm-update-package-lock
+	cmake --build $(BUILD_DIR)/documentation --target cpm-update-package-lock
 
 # install the library to stagedir
 install:
-	cmake -S . -B build/$@ ${CMAKE_PRESET} -DCMAKE_INSTALL_PREFIX=${STAGEDIR} -DCMAKE_CXX_STANDARD=20 #NO! -DCMAKE_CXX_CLANG_TIDY=clang-tidy # --trace-expand
-	cmake --build build/$@ --target $@
-	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' build/$@/compile_commands.json
-	run-clang-tidy.py -p build/$@ source    # Note: only local sources! CK
+	cmake -S . -B $(BUILD_DIR)/$@ ${CMAKE_PRESET} -DCMAKE_INSTALL_PREFIX=$(STAGE_DIR) -DCMAKE_CXX_STANDARD=20 #NO! -DCMAKE_CXX_CLANG_TIDY=clang-tidy # --trace-expand
+	cmake --build $(BUILD_DIR)/$@ --target $@
+	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' $(BUILD_DIR)/$@/compile_commands.json
+	run-clang-tidy.py -p $(BUILD_DIR)/$@ -quiet -header-filter='$(CURDIR)/.*' source    # Note: only local sources! CK
 
 # test the library
 test: install
-	cmake -S $@ -B build/$@ ${CMAKE_PRESET} -DTEST_INSTALLED_VERSION=1
-	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' build/$@/compile_commands.json
-	cmake --build build/$@
-	cmake --build build/$@ --target $@
-	run-clang-tidy.py -p build/$@ test/source    # Note: only local sources! CK
+	cmake -S $@ -B $(BUILD_DIR)/$@ ${CMAKE_PRESET} -DTEST_INSTALLED_VERSION=1
+	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' $(BUILD_DIR)/$@/compile_commands.json
+	cmake --build $(BUILD_DIR)/$@
+	cmake --build $(BUILD_DIR)/$@ --target $@
+	run-clang-tidy.py -p $(BUILD_DIR)/$@ -quiet -header-filter='$(CURDIR)/.*' test/source    # Note: only local sources! CK
 
 # all together
-all: format
-	cmake -S $@ -B build/$@ ${CMAKE_PRESET} -DENABLE_TEST_COVERAGE=1 # Note: NO! -DUSE_STATIC_ANALYZER=clang-tidy CK
-	cmake --build build/$@
-	cmake --build build/$@ --target test
+all:
+	cmake -S $@ -B $(BUILD_DIR)/$@ ${CMAKE_PRESET} -DENABLE_TEST_COVERAGE=1 # Note: NO! -DUSE_STATIC_ANALYZER=clang-tidy CK
+	cmake --build $(BUILD_DIR)/$@
+	cmake --build $(BUILD_DIR)/$@ --target test
 
 # GenerateDocs
 doc:
-	cmake -S documentation -B build/documentation "${CMAKE_PRESET}"
-	cmake --build build/documentation --target GenerateDocs
+	cmake -S documentation -B $(BUILD_DIR)/documentation "${CMAKE_PRESET}"
+	cmake --build $(BUILD_DIR)/documentation --target GenerateDocs
 
 format: distclean
 	find . -name CMakeLists.txt | xargs cmake-format -i
-	find . -name '*.cmake' | xargs cmake-format -i
+	find . -type f -name '*.cmake' | xargs cmake-format -i
 	find . -name '*.cpp' | xargs clang-format -i
 	find . -name '*.h' | xargs clang-format -i
 
 standalone:
-	cmake -S $@ -B build/$@ ${CMAKE_PRESET}
-	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' build/$@/compile_commands.json
-	cmake --build build/$@
+	cmake -S $@ -B $(BUILD_DIR)/$@ ${CMAKE_PRESET}
+	perl -i.bak -pe 's#-I($$CPM_SOURCE_CACHE)#-isystem $$1#g' $(BUILD_DIR)/$@/compile_commands.json
+	cmake --build $(BUILD_DIR)/$@
 
 # check the library
 check: standalone
-	builddriver run-clang-tidy.py -p build/standalone -checks='-*,modernize-*,misc-*,hicpp-*,cert-*,readability-*,portability-*,performance-*,google-*' standalone
+	run-clang-tidy.py -p $(BUILD_DIR)/standalone -quiet -header-filter='$(CURDIR)/.*' -checks='-*,modernize-*,misc-*,hicpp-*,cert-*,readability-*,portability-*,performance-*,google-*' standalone