diff --git a/library/alignment.h b/library/alignment.h
index d3041333824..b51656d5eb1 100644
--- a/library/alignment.h
+++ b/library/alignment.h
@@ -280,7 +280,7 @@ static inline void mbedtls_put_unaligned_uint64(void *p, uint64_t x)
 /*
  * Detect GCC built-in byteswap routines
  */
-#if defined(__GNUC__)
+#if defined(MBEDTLS_COMPILER_IS_GCC)
 #if MBEDTLS_GCC_VERSION >= 40800
 #define MBEDTLS_BSWAP16 __builtin_bswap16
 #endif
@@ -288,7 +288,7 @@ static inline void mbedtls_put_unaligned_uint64(void *p, uint64_t x)
 #define MBEDTLS_BSWAP32 __builtin_bswap32
 #define MBEDTLS_BSWAP64 __builtin_bswap64
 #endif
-#endif /* defined(__GNUC__) */
+#endif /* defined(MBEDTLS_COMPILER_IS_GCC) */
 
 /*
  * Detect Clang built-in byteswap routines