diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index fbf938d..69f1689 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -63,7 +63,7 @@
     MBEDTLS_MD_RIPEMD160, /**< The RIPEMD-160 message digest. */
 } mbedtls_md_type_t;
 
-#if defined(MBEDTLS_SHA512_C)
+#if defined(MBEDTLS_SHA512_C) || defined(MBEDTLS_SHA384_C)
 #define MBEDTLS_MD_MAX_SIZE         64  /* longest known is SHA512 */
 #else
 #define MBEDTLS_MD_MAX_SIZE         32  /* longest known is SHA256 or less */