diff --git a/include/mbedtls/padlock.h b/include/mbedtls/padlock.h
index f05b72b..721a5d4 100644
--- a/include/mbedtls/padlock.h
+++ b/include/mbedtls/padlock.h
@@ -59,7 +59,7 @@
 #define MBEDTLS_PADLOCK_PHE 0x0C00
 #define MBEDTLS_PADLOCK_PMM 0x3000
 
-#define MBEDTLS_PADLOCK_ALIGN16(x) (uint32_t *) (16 + ((int32_t) x & ~15))
+#define MBEDTLS_PADLOCK_ALIGN16(x) (uint32_t *) (16 + ((int32_t) (x) & ~15))
 
 #ifdef __cplusplus
 extern "C" {