diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index 48923e5..e8d0ab7 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -59,8 +59,10 @@
     uint64_t total[2];          /*!< The number of Bytes processed. */
     uint64_t state[8];          /*!< The intermediate digest state. */
     unsigned char buffer[128];  /*!< The data block being processed. */
+#if !defined(MBEDTLS_SHA512_NO_SHA384)
     int is384;                  /*!< Determines which function to use:
                                      0: Use SHA-512, or 1: Use SHA-384. */
+#endif
 }
 mbedtls_sha512_context;