diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 56ad01c..f1b6605 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -983,6 +983,16 @@
 //#define MBEDTLS_SHA256_SMALLER
 
 /**
+ * \def MBEDTLS_SHA512_SMALLER
+ *
+ * Enable an implementation of SHA-512 that has lower ROM footprint but also
+ * lower performance.
+ *
+ * Uncomment to enable the smaller implementation of SHA512.
+ */
+//#define MBEDTLS_SHA512_SMALLER
+
+/**
  * \def MBEDTLS_THREADING_ALT
  *
  * Provide your own alternate threading implementation.