diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 7c06815..80a4fef 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2334,6 +2334,17 @@
 #define MBEDTLS_SHA512_C
 
 /**
+ * \def MBEDTLS_SSL_ASYNC_PRIVATE_C
+ *
+ * Enable asynchronous external private key operations in SSL. This allows
+ * you to configure an SSL connection to call an external cryptographic
+ * module to perform private key operations instead of performing the
+ * operation inside the library.
+ *
+ */
+#define MBEDTLS_SSL_ASYNC_PRIVATE_C
+
+/**
  * \def MBEDTLS_SSL_CACHE_C
  *
  * Enable simple SSL cache implementation.