diff --git a/.github/workflows/dist_publish.yml b/.github/workflows/dist_publish.yml
index ce86618..d1396c6 100644
--- a/.github/workflows/dist_publish.yml
+++ b/.github/workflows/dist_publish.yml
@@ -11,6 +11,9 @@ on:
 jobs:
   build_llvm_win:
     name: Build LLVM release for Windows
+    strategy:
+      matrix:
+        arch: [x64, x86]
     runs-on: windows-latest
     steps:
     - name: Cache LLVM
@@ -20,7 +23,7 @@ jobs:
         path: llvm/install
         # TODO: would be really better to add the hash of the LLVM commit cloned
         # TODO: add "14.16" as a variable easy to replace
-        key: ${{ runner.os }}-llvm-release-11-msvc1416
+        key: ${{ runner.os }}-llvm-release-11-msvc1416-${{ matrix.arch }}
     - name: Get LLVM
       if: steps.cache-llvm.outputs.cache-hit != 'true'
       uses: actions/checkout@v2
@@ -32,6 +35,7 @@ jobs:
       if: steps.cache-llvm.outputs.cache-hit != 'true'
       with:
         toolset: "14.16"
+        arch: ${{ matrix.arch }}
     - name: Build LLVM
       if: steps.cache-llvm.outputs.cache-hit != 'true'
       run: |
@@ -143,9 +147,12 @@ jobs:
         os:
           - macos-latest
           - windows-latest
+        arch: [x64, x86]
         exclude:
           - os: windows-latest
             python-version: 2.7
+          - os: macos-latest
+            arch: x86
 
     runs-on: ${{ matrix.os }}
     needs: build_llvm_win
@@ -155,18 +162,20 @@ jobs:
     - uses: ilammy/msvc-dev-cmd@v1
       with:
         toolset: "14.16"
+        arch: ${{ matrix.arch }}
       if: runner.os == 'Windows'
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
+        architecture: ${{ matrix.arch }}
     - name: Cache LLVM
       if: runner.os == 'Windows'
       id: cache-llvm
       uses: actions/cache@v2
       with:
         path: llvm/install
-        key: ${{ runner.os }}-llvm-release-11-msvc1416
+        key: ${{ runner.os }}-llvm-release-11-msvc1416-${{ matrix.arch }}
     - name: Python dependencies
       run: |
         pip install wheel
diff --git a/include/dffi/compat.h b/include/dffi/compat.h
index a07d5e2..66f155b 100644
--- a/include/dffi/compat.h
+++ b/include/dffi/compat.h
@@ -40,8 +40,15 @@
 #endif
 
 #if defined(_MSC_VER)
-#include <BaseTsd.h>
-typedef SSIZE_T ssize_t;
+// LLVM's C API defines "by hand" ssize_t. We need to do the same otherwise we
+// got a conflicting type...
+// #include <BaseTsd.h>
+// typedef SSIZE_T ssize_t;
+#if defined(_WIN64)
+typedef signed __int64 ssize_t;
+#else
+typedef signed int ssize_t;
+#endif /* _WIN64 */
 #endif