diff --git a/include/mbedtls/build_info.h b/include/mbedtls/build_info.h
index 4f72669..891a7b5 100644
--- a/include/mbedtls/build_info.h
+++ b/include/mbedtls/build_info.h
@@ -74,6 +74,11 @@
 #define MBEDTLS_ARCH_IS_X86
 #endif
 
+#if !defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64) && \
+    (defined(_M_ARM64) || defined(_M_ARM64EC))
+#define MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64
+#endif
+
 /* This is defined if the architecture is Armv8-A, or higher */
 #if !defined(MBEDTLS_ARCH_IS_ARMV8_A)
 #if defined(__ARM_ARCH) && defined(__ARM_ARCH_PROFILE)
diff --git a/library/aesce.c b/library/aesce.c
index 8b42b03..21ec47d 100644
--- a/library/aesce.c
+++ b/library/aesce.c
@@ -26,7 +26,7 @@
  * By defining the macros ourselves we gain access to those declarations without
  * requiring -march on the command line.
  *
- * `arm_neon.h` could be included by any header file, so we put these defines
+ * `arm_neon.h` is included by common.h, so we put these defines
  * at the top of this file, before any includes.
  */
 #define __ARM_FEATURE_CRYPTO 1
@@ -66,9 +66,7 @@
 #   endif
 #endif
 
-#ifdef __ARM_NEON
-#include <arm_neon.h>
-#else
+#if !defined(MBEDTLS_HAVE_NEON_INTRINSICS)
 #error "Target does not support NEON instructions"
 #endif
 
diff --git a/library/alignment.h b/library/alignment.h
index ab15986..d8c4fb3 100644
--- a/library/alignment.h
+++ b/library/alignment.h
@@ -35,11 +35,16 @@
  * efficient when this is not defined.
  */
 #if defined(__ARM_FEATURE_UNALIGNED) \
-    || defined(__i386__) || defined(__amd64__) || defined(__x86_64__)
+    || defined(MBEDTLS_ARCH_IS_X86) || defined(MBEDTLS_ARCH_IS_X64) \
+    || defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
 /*
  * __ARM_FEATURE_UNALIGNED is defined where appropriate by armcc, gcc 7, clang 9
  * (and later versions) for Arm v7 and later; all x86 platforms should have
  * efficient unaligned access.
+ *
+ * https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=msvc-170#alignment
+ * specifies that on Windows-on-Arm64, unaligned access is safe (except for uncached
+ * device memory).
  */
 #define MBEDTLS_EFFICIENT_UNALIGNED_ACCESS
 #endif
diff --git a/library/bignum.c b/library/bignum.c
index 7c265e0..795952c 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -114,7 +114,8 @@
  * about whether the assignment was made or not.
  * (Leaking information about the respective sizes of X and Y is ok however.)
  */
-#if defined(_MSC_VER) && defined(_M_ARM64) && (_MSC_FULL_VER < 193131103)
+#if defined(_MSC_VER) && defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64) && \
+    (_MSC_FULL_VER < 193131103)
 /*
  * MSVC miscompiles this function if it's inlined prior to Visual Studio 2022 version 17.1. See:
  * https://developercommunity.visualstudio.com/t/c-compiler-miscompiles-part-of-mbedtls-library-on/1646989
diff --git a/library/common.h b/library/common.h
index 570b97e..76f282b 100644
--- a/library/common.h
+++ b/library/common.h
@@ -33,7 +33,11 @@
 
 #if defined(__ARM_NEON)
 #include <arm_neon.h>
-#endif /* __ARM_NEON */
+#define MBEDTLS_HAVE_NEON_INTRINSICS
+#elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
+#include <arm64_neon.h>
+#define MBEDTLS_HAVE_NEON_INTRINSICS
+#endif
 
 /** Helper to define a function as static except when building invasive tests.
  *
@@ -181,14 +185,14 @@
 {
     size_t i = 0;
 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
-#if defined(__ARM_NEON)
+#if defined(MBEDTLS_HAVE_NEON_INTRINSICS)
     for (; (i + 16) <= n; i += 16) {
         uint8x16_t v1 = vld1q_u8(a + i);
         uint8x16_t v2 = vld1q_u8(b + i);
         uint8x16_t x = veorq_u8(v1, v2);
         vst1q_u8(r + i, x);
     }
-#elif defined(__amd64__) || defined(__x86_64__) || defined(__aarch64__)
+#elif defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
     /* This codepath probably only makes sense on architectures with 64-bit registers */
     for (; (i + 8) <= n; i += 8) {
         uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
@@ -227,7 +231,7 @@
 {
     size_t i = 0;
 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
-#if defined(__amd64__) || defined(__x86_64__) || defined(__aarch64__)
+#if defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
     /* This codepath probably only makes sense on architectures with 64-bit registers */
     for (; (i + 8) <= n; i += 8) {
         uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
diff --git a/library/sha256.c b/library/sha256.c
index 596b2c5..c9be734 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -40,7 +40,7 @@
  * By defining the macros ourselves we gain access to those declarations without
  * requiring -march on the command line.
  *
- * `arm_neon.h` could be included by any header file, so we put these defines
+ * `arm_neon.h` is included by common.h, so we put these defines
  * at the top of this file, before any includes.
  */
 #define __ARM_FEATURE_CRYPTO 1
@@ -74,9 +74,7 @@
 
 #  if defined(MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT) || \
     defined(MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_ONLY)
-#       ifdef __ARM_NEON
-#           include <arm_neon.h>
-#       else
+#       if !defined(MBEDTLS_HAVE_NEON_INTRINSICS)
 #           if defined(MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT)
 #               warning "Target does not support NEON instructions"
 #               undef MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT
@@ -138,12 +136,7 @@
 #      include <signal.h>
 #    endif
 #  endif
-#elif defined(_M_ARM64)
-#  if defined(MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT) || \
-    defined(MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_ONLY)
-#    include <arm64_neon.h>
-#  endif
-#else
+#elif !defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
 #  undef MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_ONLY
 #  undef MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_IF_PRESENT
 #endif
@@ -168,7 +161,7 @@
 {
     return 1;
 }
-#elif defined(_M_ARM64)
+#elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
 #define WIN32_LEAN_AND_MEAN
 #include <Windows.h>
 #include <processthreadsapi.h>
diff --git a/library/sha512.c b/library/sha512.c
index e739af2..05b8940 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -31,7 +31,7 @@
  * By defining the macros ourselves we gain access to those declarations without
  * requiring -march on the command line.
  *
- * `arm_neon.h` could be included by any header file, so we put these defines
+ * `arm_neon.h` is included by common.h, so we put these defines
  * at the top of this file, before any includes.
  */
 #define __ARM_FEATURE_SHA512 1
@@ -60,9 +60,7 @@
 #  if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT) || \
     defined(MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY)
 /* *INDENT-OFF* */
-#   ifdef __ARM_NEON
-#       include <arm_neon.h>
-#   else
+#   if !defined(MBEDTLS_HAVE_NEON_INTRINSICS)
 #       error "Target does not support NEON instructions"
 #   endif
 /*
@@ -121,12 +119,7 @@
 #      include <signal.h>
 #    endif
 #  endif
-#elif defined(_M_ARM64)
-#  if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT) || \
-    defined(MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY)
-#    include <arm64_neon.h>
-#  endif
-#else
+#elif !defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
 #  undef MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY
 #  undef MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
 #endif
@@ -154,7 +147,7 @@
                            NULL, 0);
     return ret == 0 && value != 0;
 }
-#elif defined(_M_ARM64)
+#elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
 /*
  * As of March 2022, there don't appear to be any PF_ARM_V8_* flags
  * available to pass to IsProcessorFeaturePresent() to check for