diff --git a/library/sha256.c b/library/sha256.c
index 55f8d63..f0eb6ad 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -101,6 +101,10 @@
 
 #  endif
 #  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT)
+#    if defined(MBEDTLS_COMPILER_IS_GCC) && !defined(MBEDTLS_ARCH_IS_ARM64)
+#           warning "GCC only supports aarch64 for MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT, using C code only"
+#           undef MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT
+#    endif
 #    if defined(__unix__)
 #      if defined(__linux__)
 /* Our preferred method of detection is getauxval() */