diff --git a/src/base/CMakeLists.txt b/src/base/CMakeLists.txt
index 2bf4aa368..67f653dc7 100644
--- a/src/base/CMakeLists.txt
+++ b/src/base/CMakeLists.txt
@@ -7,6 +7,7 @@ add_library(qbt_base STATIC
     bittorrent/addtorrentparams.h
     bittorrent/bandwidthscheduler.h
     bittorrent/cachestatus.h
+    bittorrent/common.h
     bittorrent/customstorage.h
     bittorrent/downloadpriority.h
     bittorrent/filterparserthread.h
diff --git a/src/base/base.pri b/src/base/base.pri
index 90b07a537..f2f17d2fc 100644
--- a/src/base/base.pri
+++ b/src/base/base.pri
@@ -1,9 +1,10 @@
 HEADERS += \
     $$PWD/algorithm.h \
     $$PWD/asyncfilestorage.h \
-    $$PWD/bittorrent/addtorrentparams.h  \
+    $$PWD/bittorrent/addtorrentparams.h \
     $$PWD/bittorrent/bandwidthscheduler.h \
     $$PWD/bittorrent/cachestatus.h \
+    $$PWD/bittorrent/common.h \
     $$PWD/bittorrent/customstorage.h \
     $$PWD/bittorrent/downloadpriority.h \
     $$PWD/bittorrent/filterparserthread.h \
diff --git a/src/base/bittorrent/common.h b/src/base/bittorrent/common.h
new file mode 100644
index 000000000..6a12cfd92
--- /dev/null
+++ b/src/base/bittorrent/common.h
@@ -0,0 +1,34 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2020  Vladimir Golovnev <glassez@yandex.ru>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#pragma once
+
+#include <QString>
+
+// TODO: Make it inline in C++17
+extern const QString QB_EXT;
diff --git a/src/base/bittorrent/customstorage.cpp b/src/base/bittorrent/customstorage.cpp
index 60766e629..e411f2d10 100644
--- a/src/base/bittorrent/customstorage.cpp
+++ b/src/base/bittorrent/customstorage.cpp
@@ -34,8 +34,7 @@
 #include <QDir>
 
 #include "base/utils/fs.h"
-
-extern const QString QB_EXT {QStringLiteral(".!qB")};
+#include "common.h"
 
 lt::storage_interface *customStorageConstructor(const lt::storage_params &params, lt::file_pool &pool)
 {
diff --git a/src/base/bittorrent/session.cpp b/src/base/bittorrent/session.cpp
index 8db43787c..9ed97f146 100644
--- a/src/base/bittorrent/session.cpp
+++ b/src/base/bittorrent/session.cpp
@@ -94,6 +94,7 @@
 #include "base/utils/net.h"
 #include "base/utils/random.h"
 #include "bandwidthscheduler.h"
+#include "common.h"
 #include "customstorage.h"
 #include "filterparserthread.h"
 #include "ltunderlyingtype.h"
diff --git a/src/base/bittorrent/torrenthandle.cpp b/src/base/bittorrent/torrenthandle.cpp
index cd4e11d80..5b34808e5 100644
--- a/src/base/bittorrent/torrenthandle.cpp
+++ b/src/base/bittorrent/torrenthandle.cpp
@@ -31,8 +31,6 @@
 
 #include <type_traits>
 
-const QString QB_EXT {QStringLiteral(".!qB")};
-
 namespace BitTorrent
 {
     uint qHash(const BitTorrent::TorrentState key, const uint seed)
diff --git a/src/base/bittorrent/torrenthandle.h b/src/base/bittorrent/torrenthandle.h
index 1960a8b3d..5b180d690 100644
--- a/src/base/bittorrent/torrenthandle.h
+++ b/src/base/bittorrent/torrenthandle.h
@@ -40,8 +40,6 @@ class QDateTime;
 class QStringList;
 class QUrl;
 
-extern const QString QB_EXT;
-
 namespace BitTorrent
 {
     enum class DownloadPriority;
diff --git a/src/base/bittorrent/torrenthandleimpl.cpp b/src/base/bittorrent/torrenthandleimpl.cpp
index d2d20c65e..e5c83a450 100644
--- a/src/base/bittorrent/torrenthandleimpl.cpp
+++ b/src/base/bittorrent/torrenthandleimpl.cpp
@@ -65,6 +65,7 @@
 #include "base/tristatebool.h"
 #include "base/utils/fs.h"
 #include "base/utils/string.h"
+#include "common.h"
 #include "downloadpriority.h"
 #include "ltunderlyingtype.h"
 #include "peeraddress.h"
@@ -72,6 +73,8 @@
 #include "session.h"
 #include "trackerentry.h"
 
+const QString QB_EXT {QStringLiteral(".!qB")};
+
 using namespace BitTorrent;
 
 #if (LIBTORRENT_VERSION_NUM >= 10200)
diff --git a/src/base/utils/fs.cpp b/src/base/utils/fs.cpp
index cfec9b96b..079dd418c 100644
--- a/src/base/utils/fs.cpp
+++ b/src/base/utils/fs.cpp
@@ -58,7 +58,7 @@
 #include <QStorageInfo>
 #include <QRegularExpression>
 
-#include "base/bittorrent/torrenthandle.h"
+#include "base/bittorrent/common.h"
 #include "base/global.h"
 
 QString Utils::Fs::toNativePath(const QString &path)
diff --git a/src/gui/previewselectdialog.cpp b/src/gui/previewselectdialog.cpp
index 89708c785..1b458d334 100644
--- a/src/gui/previewselectdialog.cpp
+++ b/src/gui/previewselectdialog.cpp
@@ -36,6 +36,7 @@
 #include <QStandardItemModel>
 #include <QTableView>
 
+#include "base/bittorrent/common.h"
 #include "base/bittorrent/torrenthandle.h"
 #include "base/preferences.h"
 #include "base/utils/fs.h"
diff --git a/src/gui/torrentcontentmodelfile.cpp b/src/gui/torrentcontentmodelfile.cpp
index d14d9cc6e..4d9e12271 100644
--- a/src/gui/torrentcontentmodelfile.cpp
+++ b/src/gui/torrentcontentmodelfile.cpp
@@ -28,7 +28,7 @@
 
 #include "torrentcontentmodelfile.h"
 
-#include "base/bittorrent/torrenthandle.h"
+#include "base/bittorrent/common.h"
 #include "torrentcontentmodelfolder.h"
 
 TorrentContentModelFile::TorrentContentModelFile(const QString &fileName, qulonglong fileSize,
diff --git a/src/gui/torrentcontentmodelfolder.cpp b/src/gui/torrentcontentmodelfolder.cpp
index 55310b25e..5e0627a43 100644
--- a/src/gui/torrentcontentmodelfolder.cpp
+++ b/src/gui/torrentcontentmodelfolder.cpp
@@ -30,7 +30,7 @@
 
 #include <QVariant>
 
-#include "base/bittorrent/torrenthandle.h"
+#include "base/bittorrent/common.h"
 #include "base/global.h"
 
 TorrentContentModelFolder::TorrentContentModelFolder(const QString &name, TorrentContentModelFolder *parent)
diff --git a/src/gui/torrentcontenttreeview.cpp b/src/gui/torrentcontenttreeview.cpp
index aaf30f57f..adf22046e 100644
--- a/src/gui/torrentcontenttreeview.cpp
+++ b/src/gui/torrentcontenttreeview.cpp
@@ -37,6 +37,7 @@
 #include <QTableView>
 #include <QThread>
 
+#include "base/bittorrent/common.h"
 #include "base/bittorrent/session.h"
 #include "base/bittorrent/torrenthandle.h"
 #include "base/bittorrent/torrentinfo.h"
diff --git a/src/webui/api/torrentscontroller.cpp b/src/webui/api/torrentscontroller.cpp
index 787c071a4..ab163afbc 100644
--- a/src/webui/api/torrentscontroller.cpp
+++ b/src/webui/api/torrentscontroller.cpp
@@ -39,6 +39,7 @@
 #include <QRegularExpression>
 #include <QUrl>
 
+#include "base/bittorrent/common.h"
 #include "base/bittorrent/downloadpriority.h"
 #include "base/bittorrent/infohash.h"
 #include "base/bittorrent/peeraddress.h"