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