diff --git a/src/common.h b/src/common.h
index 0ed0d11..4ccd272 100644
--- a/src/common.h
+++ b/src/common.h
@@ -1,131 +1,134 @@
 /* common.h - Common declarations for GpgOL
  * Copyright (C) 2004 Timo Schulz
  * Copyright (C) 2005, 2006, 2007, 2008 g10 Code GmbH
  * Copyright (C) 2015, 2016 by Bundesamt für Sicherheit in der Informationstechnik
  * Software engineering by Intevation GmbH
  *
  * This file is part of GpgOL.
  *
  * GpgOL is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
  * as published by the Free Software Foundation; either version 2.1
  * of the License, or (at your option) any later version.
  *
  * GpgOL is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef GPGOL_COMMON_H
 #define GPGOL_COMMON_H
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif
 
 #include <gpgme.h>
 
 #include "common_indep.h"
 
 #include <windows.h>
 
 /* i18n stuff */
 #include "w32-gettext.h"
 #define _(a) gettext (a)
 #define N_(a) gettext_noop (a)
 
 
 /* Registry path to store plugin settings */
 #define GPGOL_REGPATH "Software\\GNU\\GpgOL"
 
 #ifdef __cplusplus
+#include <string.h>
+std::string readRegStr (const char *root, const char *dir, const char *name);
+
 extern "C" {
 #if 0
 }
 #endif
 #endif
 extern HINSTANCE glob_hinst;
 extern UINT      this_dll;
 
 /*-- common.c --*/
 void set_global_hinstance (HINSTANCE hinst);
 
 char *get_data_dir (void);
 char *get_gpg4win_dir (void);
 
 int store_extension_value (const char *key, const char *val);
 int store_extension_subkey_value (const char *subkey, const char *key,
                                   const char *val);
 int load_extension_value (const char *key, char **val);
 
 /* Get a temporary filename with and its name */
 wchar_t *get_tmp_outfile (wchar_t *name, HANDLE *outHandle);
 
 wchar_t *get_pretty_attachment_name (wchar_t *path, protocol_t protocol,
                                      int signature);
 
 /*-- verify-dialog.c --*/
 int verify_dialog_box (gpgme_protocol_t protocol,
                        gpgme_verify_result_t res,
                        const char *filename);
 
 
 /*-- inspectors.cpp --*/
 int initialize_inspectors (void);
 
 #if __GNUC__ >= 4
 # define GPGOL_GCC_A_SENTINEL(a) __attribute__ ((sentinel(a)))
 #else
 # define GPGOL_GCC_A_SENTINEL(a)
 #endif
 
 
 /*-- common.c --*/
 
 void fatal_error (const char *format, ...);
 
 char *read_w32_registry_string (const char *root, const char *dir,
                                 const char *name);
 char *percent_escape (const char *str, const char *extra);
 
 void fix_linebreaks (char *str, int *len);
 
 /* Format a date from gpgme (seconds since epoch)
    with windows system locale. */
 char *format_date_from_gpgme (unsigned long time);
 
 /* Get the name of the uiserver */
 char *get_uiserver_name (void);
 
 int is_elevated (void);
 
 /*-- main.c --*/
 void read_options (void);
 int write_options (void);
 
 extern int g_ol_version_major;
 
 void bring_to_front (HWND wid);
 
 int gpgol_message_box (HWND parent, const char *utf8_text,
                        const char *utf8_caption, UINT type);
 
 /* Show a bug message with the code. */
 void gpgol_bug (HWND parent, int code);
 
 void i18n_init (void);
 #define ERR_CRYPT_RESOLVER_FAILED 1
 #define ERR_WANTS_SEND_MIME_BODY 2
 #define ERR_WANTS_SEND_INLINE_BODY 3
 #define ERR_INLINE_BODY_TO_BODY 4
 #define ERR_INLINE_BODY_INV_STATE 5
 #define ERR_SEND_FALLBACK_FAILED 6
 #define ERR_GET_BASE_MSG_FAILED 7
 #ifdef __cplusplus
 }
 #endif
 #endif /*GPGOL_COMMON_H*/