diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 2509cff..1e6fff5 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -19,6 +19,7 @@
 #if !defined(MBEDTLS_SSL_TLS1_3_KEYS_H)
 #define MBEDTLS_SSL_TLS1_3_KEYS_H
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
 /* This requires MBEDTLS_SSL_TLS1_3_LABEL( idx, name, string ) to be defined at
  * the point of use. See e.g. the definition of mbedtls_ssl_tls1_3_labels_union
  * below. */
@@ -631,4 +632,5 @@
                                       size_t *actual_len,
                                       int from );
 
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 #endif /* MBEDTLS_SSL_TLS1_3_KEYS_H */