diff --git a/src/utils/assuan.h b/src/utils/assuan.h
index eee35e04d..ebfe580ce 100644
--- a/src/utils/assuan.h
+++ b/src/utils/assuan.h
@@ -1,72 +1,73 @@
 /*
     utils/assuan.h
 
     This file is part of libkleopatra
     SPDX-FileCopyrightText: 2021, 2022 g10 Code GmbH
     SPDX-FileContributor: Ingo Klöcker <dev@ingo-kloecker.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #pragma once
 
 #include "kleo_export.h"
 
 #include <memory>
+#include <string>
 #include <vector>
 
 namespace GpgME
 {
 class AssuanTransaction;
 class Context;
 class DefaultAssuanTransaction;
 class Error;
 }
 
 namespace Kleo
 {
 /** The Assuan namespace collects functions for communicating with the GnuPG
  *  agent via the Assuan protocol. */
 namespace Assuan
 {
 
 /** Checks if the GnuPG agent is running and accepts connections. */
 KLEO_EXPORT bool agentIsRunning();
 
 /** Sends the Assuan @p command using the @p transaction and the @p assuanContext
  *  to the GnuPG agent and waits for the result. The returned transaction can be used
  *  to retrieve the result.
  *  If an error occurred, then @p err provides details. */
 KLEO_EXPORT std::unique_ptr<GpgME::AssuanTransaction> sendCommand(std::shared_ptr<GpgME::Context> &assuanContext,
                                                                   const std::string &command,
                                                                   std::unique_ptr<GpgME::AssuanTransaction> transaction,
                                                                   GpgME::Error &err);
 
 /** Sends the Assuan @p command using a default Assuan transaction and the @p assuanContext
  *  to the GnuPG agent and waits for the result. The returned transaction can be used
  *  to retrieve the result.
  *  If an error occurred, then @p err provides details. */
 KLEO_EXPORT std::unique_ptr<GpgME::DefaultAssuanTransaction>
 sendCommand(std::shared_ptr<GpgME::Context> &assuanContext, const std::string &command, GpgME::Error &err);
 
 /** Sends the Assuan @p command using a default Assuan transaction and the @p assuanContext
  *  to the GnuPG agent and waits for the result. Returns the data that was sent by
  *  GnuPG agent in response to the @p command.
  *  If an error occurred, then @p err provides details. */
 KLEO_EXPORT std::string sendDataCommand(std::shared_ptr<GpgME::Context> assuanContext, const std::string &command, GpgME::Error &err);
 
 /** Sends the Assuan @p command using a default Assuan transaction and the @p assuanContext
  *  to the GnuPG agent and waits for the result. Returns the status lines that were sent by
  *  GnuPG agent in response to the @p command.
  *  If an error occurred, then @p err provides details. */
 KLEO_EXPORT std::vector<std::pair<std::string, std::string>>
 sendStatusLinesCommand(std::shared_ptr<GpgME::Context> assuanContext, const std::string &command, GpgME::Error &err);
 
 /** Sends the Assuan @p command using a default Assuan transaction and the @p assuanContext
  *  to the GnuPG agent and waits for the result. Returns the status that was sent by
  *  GnuPG agent in response to the @p command.
  *  If an error occurred, then @p err provides details. */
 KLEO_EXPORT std::string sendStatusCommand(const std::shared_ptr<GpgME::Context> &assuanContext, const std::string &command, GpgME::Error &err);
 
 }
 }