diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index d454ebb..581e153 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -2058,9 +2058,10 @@
 #endif /* MBEDTLS_ECDH_C */
 
 #if defined(MBEDTLS_SSL_EARLY_DATA)
-int mbedtls_ssl_tls13_write_early_data_ext(
-    mbedtls_ssl_context *ssl,
-    unsigned char *buf, const unsigned char *end, size_t *olen);
+int mbedtls_ssl_tls13_write_early_data_ext( mbedtls_ssl_context *ssl,
+                                            unsigned char *buf,
+                                            const unsigned char *end,
+                                            size_t *out_len );
 #endif /* MBEDTLS_SSL_EARLY_DATA */
 
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */