diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f4a6623..bcd970c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -120,10 +120,11 @@ jobs:
         env:
           HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK: 1
         run: |
-          brew install --quiet ninja capnp
+          brew install --quiet ninja capnp llvm
 
       - name: Run CI script
         run: |
+          export PATH="$(brew --prefix llvm)/bin:$PATH"
           CI_CONFIG="ci/configs/macos.bash" bash ci/scripts/ci.sh
 
   build:
diff --git a/ci/configs/macos.bash b/ci/configs/macos.bash
index a444bac..895d795 100644
--- a/ci/configs/macos.bash
+++ b/ci/configs/macos.bash
@@ -1,5 +1,5 @@
 CI_DESC="CI config for macOS"
 CI_DIR=build-macos
 export CXXFLAGS="-Werror -Wall -Wextra -Wpedantic -Wno-unused-parameter"
-CMAKE_ARGS=(-G Ninja)
+CMAKE_ARGS=(-G Ninja -DMP_ENABLE_CLANG_TIDY=ON)
 BUILD_ARGS=(-k 0)
diff --git a/cmake/pthread_checks.cmake b/cmake/pthread_checks.cmake
index 241978d..8771141 100644
--- a/cmake/pthread_checks.cmake
+++ b/cmake/pthread_checks.cmake
@@ -25,7 +25,7 @@ check_cxx_source_compiles("
   int main(int argc, char** argv)
   {
     uint64_t tid;
-    pthread_threadid_np(NULL, &tid);
+    pthread_threadid_np(nullptr, &tid);
     return 0;
   }"
   HAVE_PTHREAD_THREADID_NP)
diff --git a/src/mp/util.cpp b/src/mp/util.cpp
index 7b48608..ad4a7f6 100644
--- a/src/mp/util.cpp
+++ b/src/mp/util.cpp
@@ -81,7 +81,7 @@ std::string ThreadName(const char* exe_name)
     buffer << syscall(SYS_gettid);
 #elif defined(HAVE_PTHREAD_THREADID_NP)
     uint64_t tid = 0;
-    pthread_threadid_np(NULL, &tid);
+    pthread_threadid_np(nullptr, &tid);
     buffer << tid;
 #elif defined(HAVE_PTHREAD_GETTHREADID_NP)
     buffer << pthread_getthreadid_np();