diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index b9f456f..b0424bf 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -1307,8 +1307,10 @@
                                          size_t msg_len );
 
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+#if !defined(MBEDTLS_USE_PSA_CRYPTO)
 int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl,
                                       mbedtls_key_exchange_type_t key_ex );
+#endif /* !MBEDTLS_USE_PSA_CRYPTO */
 #if defined(MBEDTLS_SSL_CLI_C) && defined(MBEDTLS_SSL_PROTO_TLS1_2)
 int mbedtls_ssl_conf_has_static_psk( mbedtls_ssl_config const *conf );
 #endif