diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000..796b96d1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b237e397..1efc98fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -74,7 +74,7 @@ endif()
 #
 #-----------------------------------------------------------------------------
 message(STATUS "Looking for clang-tidy")
-find_program(CLANG_TIDY NAMES clang-tidy-20 clang-tidy-19 clang-tidy-18 clang-tidy-17 clang-tidy-16 clang-tidy-15)
+find_program(CLANG_TIDY NAMES clang-tidy-20 clang-tidy-19 clang-tidy-18 clang-tidy-17 clang-tidy-16 clang-tidy-15 clang-tidy)
 
 if(CLANG_TIDY AND PROTOBUF_FOUND)
     message(STATUS "Looking for clang-tidy - found ${CLANG_TIDY}")
@@ -93,6 +93,10 @@ if(CLANG_TIDY AND PROTOBUF_FOUND)
 else()
     message(STATUS "Looking for clang-tidy - not found")
     message(STATUS "  Build target 'clang-tidy' will not be available.")
+    add_custom_target(clang-tidy
+        COMMAND ${CMAKE_COMMAND} -E echo "ERROR: clang-tidy not found. Install it and re-run cmake."
+        COMMAND false
+        VERBATIM)
 endif()
 
 
@@ -118,7 +122,10 @@ if(CPPCHECK)
     )
 else()
     message(STATUS "Looking for cppcheck - not found")
-    message(STATUS "  Build target 'cppcheck' will not be available.")
+    add_custom_target(cppcheck
+        COMMAND ${CMAKE_COMMAND} -E echo "ERROR: cppcheck not found. Install it and re-run cmake."
+        COMMAND false
+        VERBATIM)
 endif()
 
 
@@ -128,16 +135,27 @@ endif()
 #
 #-----------------------------------------------------------------------------
 message(STATUS "Looking for iwyu")
-find_program(IWYU_TOOL NAMES iwyu_tool)
+find_program(IWYU_TOOL NAMES iwyu_tool iwyu_tool.py)
 
 if(IWYU_TOOL)
     message(STATUS "Looking for iwyu - found")
+    set(IWYU_EXTRA_ARGS)
+    if(APPLE)
+        execute_process(COMMAND xcrun --show-sdk-path
+            OUTPUT_VARIABLE IWYU_SDK_PATH
+            OUTPUT_STRIP_TRAILING_WHITESPACE)
+        list(APPEND IWYU_EXTRA_ARGS -isysroot ${IWYU_SDK_PATH} -Wno-c2y-extensions)
+    endif()
     add_custom_target(iwyu
-        ${IWYU_TOOL} -p ${CMAKE_BINARY_DIR}
+        ${IWYU_TOOL} -p ${CMAKE_BINARY_DIR} -- ${IWYU_EXTRA_ARGS}
     )
 else()
     message(STATUS "Looking for iwyu - not found")
     message(STATUS "  Build target 'iwyu' will not be available.")
+    add_custom_target(iwyu
+        COMMAND ${CMAKE_COMMAND} -E echo "ERROR: iwyu not found. Install it and re-run cmake."
+        COMMAND false
+        VERBATIM)
 endif()
 
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 02605de5..7d43ed2d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -5,7 +5,7 @@
 To release a new protozero version:
 
  - Make sure all tests are passing locally and on Github Actions
- - Make sure "make doc" builds
+ - Make sure `cmake --build build --target doc` builds
  - Update version number in
    - include/protozero/version.hpp (two places)
    - CMakeLists.txt (one place)
diff --git a/README.md b/README.md
index 15c9ddee..5adc2a9b 100644
--- a/README.md
+++ b/README.md
@@ -71,12 +71,10 @@ tell us about your system.
 
 Extensive tests are included. Build them using CMake:
 
-    mkdir build
-    cd build
-    cmake ..
-    make
+    cmake -Bbuild
+    cmake --build build
 
-Call `ctest` to run the tests.
+Call `ctest -test-dir build` to run the tests.
 
 The unit and reader tests are always build, the writer tests are only build if
 the Google Protobuf library is found when running CMake.
@@ -88,9 +86,9 @@ See `test/README.md` for more details about the test.
 
 To get a coverage report set `CXXFLAGS` and `LDFLAGS` before calling CMake:
 
-    CXXFLAGS="--coverage" LDFLAGS="--coverage" cmake ..
+    CXXFLAGS="--coverage" LDFLAGS="--coverage" cmake -Bbuild
 
-Then call `make` as usual and run the tests using `ctest`.
+Then call `cmake --build build` as usual and run the tests using `ctest -test-dir build`.
 
 If you are using `g++` use `gcov` to generate a report (results are in `*.gcov`
 files):
@@ -113,7 +111,7 @@ Open `coverage/index.html` in your browser to see the report.
 
 After the CMake step, run
 
-    make clang-tidy
+    cmake --build build --target clang-tidy
 
 to check the code with [clang-tidy](https://clang.llvm.org/extra/clang-tidy/).
 You might have to set `CLANG_TIDY` in CMake config.
@@ -124,12 +122,20 @@ You might have to set `CLANG_TIDY` in CMake config.
 For extra checks with [Cppcheck](https://cppcheck.sourceforge.io/) you can,
 after the CMake step, call
 
-    make cppcheck
+    cmake --build build --target cppcheck
+
+
+## Include What You Use
+
+For checking `#include` hygiene with [include-what-you-use](https://include-what-you-use.org/)
+you can, after the CMake step, call
+
+    cmake --build build --target iwyu
 
 
 ## Installation
 
-After the CMake step, call `make install` to install the include files in
+After the CMake step, call `cmake --build build --target install` to install the include files in
 `/usr/local/include/protozero`.
 
 If you are using CMake to build your own software, you can copy the file
diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
index 133fb3e6..81cff615 100644
--- a/doc/CMakeLists.txt
+++ b/doc/CMakeLists.txt
@@ -28,6 +28,10 @@ if(DOXYGEN_FOUND AND DOXYGEN_DOT_FOUND)
 else()
     message(STATUS "Looking for doxygen - not found")
     message(STATUS "  Disabled making of documentation.")
+    add_custom_target(doc
+        COMMAND ${CMAKE_COMMAND} -E echo "ERROR: doxygen (or graphviz/dot) not found. Install them and re-run cmake."
+        COMMAND false
+        VERBATIM)
 endif()
 
 #-----------------------------------------------------------------------------
diff --git a/doc/advanced.md b/doc/advanced.md
index d579538d..60089dba 100644
--- a/doc/advanced.md
+++ b/doc/advanced.md
@@ -169,7 +169,7 @@ decode_zigzag32()
 decode_zigzag64()
 ```
 
-See the reference documentation created by `make doc` for details.
+See the reference documentation created by `cmake --build build --target doc` for details.
 
 
 ## Vectored input for length-delimited fields
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 3dbd96d1..b9a8c2da 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -96,6 +96,11 @@ if(PROTOBUF_FOUND)
         endif()
     endforeach()
 
+    if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+        # Google Protobuf library adds non-standard _Nonnull to Abseil macros
+        set_source_files_properties(${PROTO_SRCS} PROPERTIES COMPILE_FLAGS "-Wno-nullability-extension")
+    endif()
+
     add_executable(writer_tests writer_tests.cpp ${SOURCES} ${PROTO_SRCS} ${PROTO_HDRS})
 
     target_compile_features(writer_tests PUBLIC cxx_std_14)