diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 966b5c5..81414d8 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -667,6 +667,23 @@
                                              size_t *actual_len,
                                              int which );
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+/**
+ * \brief Compute TLS 1.3 early transform
+ *
+ * \param ssl  The SSL context to operate on. The early secret must have been
+ *             computed.
+ *
+ * \returns    \c 0 on success.
+ * \returns    A negative error code on failure.
+ *
+ * \warning   `early_secrets` is not computation. Caller MUST call
+ *            mbedtls_ssl_tls13_key_schedule_stage_early() before this function.
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+int mbedtls_ssl_tls13_compute_early_transform( mbedtls_ssl_context *ssl );
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 /**
  * \brief Compute TLS 1.3 handshake transform
  *