diff --git a/src/libsodium/crypto_aead/aes256gcm/armcrypto/aead_aes256gcm_armcrypto.c b/src/libsodium/crypto_aead/aes256gcm/armcrypto/aead_aes256gcm_armcrypto.c
index aa76f5cd..85ab45d4 100644
--- a/src/libsodium/crypto_aead/aes256gcm/armcrypto/aead_aes256gcm_armcrypto.c
+++ b/src/libsodium/crypto_aead/aes256gcm/armcrypto/aead_aes256gcm_armcrypto.c
@@ -15,7 +15,7 @@
 
 #if defined(HAVE_ARMCRYPTO) && defined(__clang__) && defined(NATIVE_LITTLE_ENDIAN)
 
-#if !defined(MSC_VER) || _MSC_VER < 1800
+#if !defined(_MSC_VER) || _MSC_VER < 1800
 #define __vectorcall
 #endif