diff --git a/projects/facebook.com/watchman/package.yml b/projects/facebook.com/watchman/package.yml
index 144edf0f..373c002a 100644
--- a/projects/facebook.com/watchman/package.yml
+++ b/projects/facebook.com/watchman/package.yml
@@ -19,7 +19,7 @@ dependencies:
   pcre.org/v2: ^10
   python.org: ~3.11
   linux:
-    llvm.org: ~17 # libunwind
+    libcxx.llvm.org: 18 # libunwind/libc++
 
 build:
   dependencies:
@@ -30,6 +30,12 @@ build:
     facebook.com/mvfst: '>=2023.12.25.0'
     rust-lang.org: '*'
   script:
+    # version/path mismatch
+    - run: |
+        if test -f Cargo.toml; then
+          sed -i 's/watchman_client = { version = ".*", path/watchman_client = { path/' Cargo.toml
+        fi
+      working-directory: watchman/cli
     - cmake -S . -B build $CMAKE_ARGS -DCMAKE_CXX_FLAGS="$CXXFLAGS"
     - cmake --build build
     - cmake --install build
@@ -45,15 +51,27 @@ build:
       - -DBUILD_TESTING=OFF
       - -DENABLE_EDEN_SUPPORT=ON
       - -DWATCHMAN_VERSION_OVERRIDE={{version}}
+      - -DPython3_EXECUTABLE={{deps.python.org.prefix}}/bin/python
     linux:
       CC: clang
-      CXXFLAGS:
-        - -fPIC
-        - -latomic
-        - -Wl,--allow-shlib-undefined
+      CXX: clang++
+      LD: clang
       CMAKE_ARGS:
         - -DCMAKE_C_FLAGS=-fPIC
-        - -DCMAKE_EXE_LINKER_FLAGS=-pie
+    linux/x86-64:
+      CXXFLAGS:
+        - -fPIC
+        - -Wl,--allow-shlib-undefined
+      CMAKE_ARGS:
+        - -DCMAKE_EXE_LINKER_FLAGS=-Wl,-pie
+    linux/aarch64:
+      CXXFLAGS:
+        - -fPIC
+        - -Wl,--allow-shlib-undefined
+        - -cxx-isystem {{deps.libcxx.llvm.org.prefix}}/include/c++/v1
+        - -stdlib=libc++
+      CMAKE_ARGS:
+        - -DCMAKE_EXE_LINKER_FLAGS=-Wl,-pie,-lc++
 
 provides:
   - bin/watchman