diff --git a/.github/workflows/wheels.yml b/.github/workflows/wheels.yml
index 200fb9d3..cd14a157 100644
--- a/.github/workflows/wheels.yml
+++ b/.github/workflows/wheels.yml
@@ -25,26 +25,37 @@ jobs:
 
   build_wheels:
     runs-on: ${{ matrix.os }}
+    # windows-11-arm is newly added; its native toolchain may not build every
+    # dependency yet (embree / predicates use x86 SIMD), so don't let that leg
+    # block a release if it fails.
+    continue-on-error: ${{ matrix.os == 'windows-11-arm' }}
     strategy:
       fail-fast: false
+      # One runner per *native* target architecture; cibuildwheel builds the
+      # runner's native arch by default. Do NOT reintroduce a cross `arch`
+      # dimension: previously `arch: arm64` on the x86 ubuntu-24.04 / windows-latest
+      # runners silently built x86_64 / amd64 wheels (only CIBW_ARCHS_MACOS was
+      # wired up), producing duplicate wheels that collided during the release
+      # artifact download and left win_arm64 uncovered.
       matrix:
-        os: [ubuntu-24.04, ubuntu-24.04-arm, macos-latest, macos-15-intel, windows-latest]  # Use specific versions for clarity
-        arch: [x86_64, arm64]
-        pybuilds: [cp38, cp39, cp310, cp311, cp312] # Define pybuilds at the top level
+        os: [ubuntu-24.04, ubuntu-24.04-arm, macos-latest, macos-15-intel, windows-latest, windows-11-arm]
+        pybuilds: [cp38, cp39, cp310, cp311, cp312]
         exclude:
-          - os: ubuntu-24.04-arm  # No need to specify arch, it's already implicit
-            arch: x86_64  # Exclude x86_64 on ARM
+          # No macOS CPython 3.8 wheels are shipped.
           - os: macos-latest
-            arch: x86_64   # Exclude x86_64 explicitly
-          - os: macos-latest # Exclude cp38
             pybuilds: cp38
           - os: macos-15-intel
-            arch: arm64   # Exclude arm64 on macOS 13
-          - os: macos-15-intel
             pybuilds: cp38
+          # Windows on ARM64 has official CPython only for 3.11+.
+          - os: windows-11-arm
+            pybuilds: cp38
+          - os: windows-11-arm
+            pybuilds: cp39
+          - os: windows-11-arm
+            pybuilds: cp310
 
     name: >
-      ${{ matrix.pybuilds }} ${{ matrix.os }} ${{ matrix.arch }}
+      ${{ matrix.pybuilds }} ${{ matrix.os }}
 
     steps:
       - uses: actions/checkout@v4
@@ -59,15 +70,21 @@ jobs:
           CIBW_ENVIRONMENT_LINUX: "CC=clang CXX=clang++"
           CIBW_MANYLINUX_X86_64_IMAGE: "manylinux_2_28"
           CIBW_MANYLINUX_AARCH64_IMAGE: "manylinux_2_28"
-          CIBW_BUILD: "${{ matrix.pybuilds }}-*"  # Use matrix.pybuilds and matrix.arch
-          CIBW_ARCHS_MACOS: ${{ matrix.arch }}
+          CIBW_BUILD: "${{ matrix.pybuilds }}-*"
+          # No CIBW_ARCHS_* override: each runner builds its native architecture.
           CIBW_SKIP: "cp*-manylinux_i686 cp*-musllinux* cp*-win32"
+          # embree only enables its NEON (sse2neon) path when its build detects an
+          # ARM target; on Windows/MSVC-ARM64 that detection falls back to SSE2 and
+          # fails to compile (x86 immintrin.h). Drop embree on win_arm64 (the
+          # igl.embree submodule is simply absent from that wheel).
+          CIBW_ENVIRONMENT_WINDOWS: ${{ matrix.os == 'windows-11-arm' && 'CMAKE_ARGS=-DLIBIGL_EMBREE=OFF' || '' }}
       - name: Upload Artifact
         uses: actions/upload-artifact@v4
         continue-on-error: true  # Important: Continue if upload fails
         with:
-          # Include pybuilds in the artifact name
-          name: wheels-${{ matrix.os }}-${{ matrix.arch }}-${{ matrix.pybuilds }}
+          # Unique per (os, python); one native arch per runner so wheel
+          # filenames never collide when the release job merges artifacts.
+          name: wheels-${{ matrix.os }}-${{ matrix.pybuilds }}
           path: ./wheelhouse/*.whl
           if-no-files-found: error  # Fail if no wheels are found
           compression-level: 6
diff --git a/pyproject.toml b/pyproject.toml
index b0cc59c2..efbeeeba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "libigl"
-version = "2.6.3"
+version = "2.6.4.dev0"
 description = "libigl: A simple C++ geometry processing library"
 readme = "README.md"
 requires-python = ">=3.8"
diff --git a/tests/test_all.py b/tests/test_all.py
index ed893aa5..868622de 100644
--- a/tests/test_all.py
+++ b/tests/test_all.py
@@ -10,11 +10,18 @@
 import igl.copyleft
 import igl.copyleft.tetgen
 import igl.copyleft.cgal
-import igl.embree
 import igl.spectra
 import igl.predicates
 import igl.cycodebase
 
+# embree is not built on every platform (e.g. Windows/ARM64, where upstream
+# embree has no MSVC build), so treat it as optional.
+try:
+    import igl.embree
+    HAS_EMBREE = True
+except ImportError:
+    HAS_EMBREE = False
+
 @pytest.fixture
 def icosahedron():
     V,F = igl.icosahedron()
@@ -569,6 +576,7 @@ def test_cgal():
 
     R = igl.copyleft.cgal.oriented_bounding_box(VC)
     
+@pytest.mark.skipif(not HAS_EMBREE, reason="igl.embree not built (e.g. Windows/ARM64)")
 def test_embree():
     # octahedron
     V = np.array([[1,0,0],[0,1,0],[0,0,1],[-1,0,0],[0,-1,0],[0,0,-1]],dtype=np.float64)
@@ -1392,6 +1400,7 @@ def test_new_tetgen_algorithms():
     assert FF_sk.shape[1] == 3
 
 
+@pytest.mark.skipif(not HAS_EMBREE, reason="igl.embree not built (e.g. Windows/ARM64)")
 def test_new_embree_algorithms():
     V_oct = np.array([[1,0,0],[0,1,0],[0,0,1],[-1,0,0],[0,-1,0],[0,0,-1]], dtype=np.float64)
     F_oct = np.array([[0,1,2],[0,2,4],[0,4,5],[0,5,1],[1,3,2],[1,5,3],[2,3,4],[3,5,4]], dtype=np.int64)