diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index c16a238..25ded98 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -987,6 +987,8 @@
 void mbedtls_ssl_optimize_checksum( mbedtls_ssl_context *ssl,
                             mbedtls_ssl_ciphersuite_handle_t ciphersuite_info );
 
+int mbedtls_ssl_build_pms( mbedtls_ssl_context *ssl );
+
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
 int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exchange_type_t key_ex );
 #endif