diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0d03169ee..e5d7f3105 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -123,6 +123,24 @@ jobs:
           make pre_gen
           make CFLAGS="-DLTM_DESC -DUSE_LTM" EXTRALIBS="-ltommath" AMALGAM=1 -j$(nproc) check
 
+  CMake-Windows:
+    name: CMake-Windows (${{ matrix.name }})
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { name: 'stock',      ltc_cflags: '' }
+          - { name: 'LTC_NO_ASM', ltc_cflags: '-DLTC_NO_ASM' }
+    steps:
+      - uses: actions/checkout@v4
+      # WITH_LTM is off because libtommath is not packaged on the Windows
+      # runner; none of the code under test here needs the MPI provider.
+      - name: configure
+        run: cmake -B build -DWITH_LTM=FALSE "-DLTC_CFLAGS=${{ matrix.ltc_cflags }}"
+      - name: build
+        run: cmake --build build --config Release
+
   CMake:
     runs-on: ${{ matrix.os }}
     strategy:
diff --git a/src/headers/tomcrypt_private.h b/src/headers/tomcrypt_private.h
index eaba82c9b..85952409f 100644
--- a/src/headers/tomcrypt_private.h
+++ b/src/headers/tomcrypt_private.h
@@ -15,15 +15,6 @@
 
 #define LTC_PAD_MASK       (0xF000U)
 
-/* only real 64bit, not ILP32 */
-#if defined(ENDIAN_64BITWORD) && !defined(ENDIAN_64BITWORD_ILP32)
-   #define CONSTPTR(n) CONST64(n)
-#else
-   #define CONSTPTR(n) n ## uL
-#endif
-
-LTC_STATIC_ASSERT(correct_CONSTPTR_size, sizeof(CONSTPTR(1)) == sizeof(void*))
-
 /* Poor-man's `uintptr_t` since we can't use stdint.h
  * c.f. https://github.com/DCIT/perl-CryptX/issues/95#issuecomment-1745280962 */
 typedef size_t ltc_uintptr;
@@ -33,7 +24,7 @@ LTC_STATIC_ASSERT(correct_ltc_uintptr_size, sizeof(ltc_uintptr) == sizeof(void*)
 /* Aligns a `unsigned char` buffer `buf` to `n` bytes and returns that aligned address.
  * Make sure that the buffer that is passed is huge enough.
  */
-#define LTC_ALIGN_BUF(buf, align) ((void*)((ltc_uintptr)&((unsigned char*)(buf))[(align) - 1] & (~(CONSTPTR(align) - CONSTPTR(1)))))
+#define LTC_ALIGN_BUF(buf, align) ((void*)((ltc_uintptr)&((unsigned char*)(buf))[(align) - 1] & ~((ltc_uintptr)(align) - (ltc_uintptr)1)))
 
 #define LTC_OID_MAX_STRLEN 256