diff --git a/Changelog b/Changelog
index 18f8d18eb..470c29c23 100644
--- a/Changelog
+++ b/Changelog
@@ -6,6 +6,7 @@
     - FEATURE: Inhibit system sleep when torrents are active (Vladimir Golovnev)
     - FEATURE: Added option to bypass Web UI authentication for localhost
     - FEATURE: Added option to disable program exit confirmation
+    - BUGFIX: Fix compilation with namespaced Qt (Christian Kandeler)
 
 * Sun Jan 9 2011 - Christophe Dumez <chris@qbittorrent.org> - v2.6.0
     - FEATURE: Use system icons (Linux, Qt >= 4.6)
diff --git a/src/downloadthread.h b/src/downloadthread.h
index 887630ca2..3115c3588 100644
--- a/src/downloadthread.h
+++ b/src/downloadthread.h
@@ -36,7 +36,9 @@
 #include <QHash>
 #include <QSslError>
 
+QT_BEGIN_NAMESPACE
 class QNetworkAccessManager;
+QT_END_NAMESPACE
 
 class DownloadThread : public QObject {
   Q_OBJECT
diff --git a/src/executionlog.h b/src/executionlog.h
index 5ceb56725..bc51e27eb 100644
--- a/src/executionlog.h
+++ b/src/executionlog.h
@@ -3,9 +3,11 @@
 
 #include <QWidget>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
     class ExecutionLog;
 }
+QT_END_NAMESPACE
 
 class ExecutionLog : public QWidget
 {
diff --git a/src/lineedit/src/lineedit.h b/src/lineedit/src/lineedit.h
index 73f351fca..a0b51959d 100644
--- a/src/lineedit/src/lineedit.h
+++ b/src/lineedit/src/lineedit.h
@@ -12,7 +12,9 @@
 
 #include <QLineEdit>
 
+QT_BEGIN_NAMESPACE
 class QToolButton;
+QT_END_NAMESPACE
 
 class LineEdit : public QLineEdit
 {
diff --git a/src/mainwindow.h b/src/mainwindow.h
index fc335fc6a..a5b4712a7 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -38,18 +38,13 @@
 #include "qtorrenthandle.h"
 
 class QBtSession;
-class QTimer;
 class downloadFromURL;
 class SearchEngine;
-class QCloseEvent;
 class RSSImp;
-class QShortcut;
 class about;
 class options_imp;
-class QTabWidget;
 class TransferListWidget;
 class TransferListFiltersWidget;
-class QSplitter;
 class PropertiesWidget;
 class StatusBar;
 class consoleDlg;
@@ -58,10 +53,18 @@ class TorrentCreatorDlg;
 class downloadFromURL;
 class HidableTabWidget;
 class LineEdit;
-class QFileSystemWatcher;
 class ExecutionLog;
 class PowerManagement;
 
+QT_BEGIN_NAMESPACE
+class QCloseEvent;
+class QFileSystemWatcher;
+class QShortcut;
+class QSplitter;
+class QTabWidget;
+class QTimer;
+QT_END_NAMESPACE
+
 class MainWindow : public QMainWindow, private Ui::MainWindow{
   Q_OBJECT
 
diff --git a/src/powermanagement/powermanagement_x11.h b/src/powermanagement/powermanagement_x11.h
index ecd68506d..963d57581 100644
--- a/src/powermanagement/powermanagement_x11.h
+++ b/src/powermanagement/powermanagement_x11.h
@@ -33,7 +33,9 @@
 
 #include <QObject>
 
+QT_BEGIN_NAMESPACE
 class QDBusPendingCallWatcher;
+QT_END_NAMESPACE
 
 class PowerManagementInhibitor : public QObject
 {
diff --git a/src/preferences/options_imp.h b/src/preferences/options_imp.h
index 0e29334e2..f255242c5 100644
--- a/src/preferences/options_imp.h
+++ b/src/preferences/options_imp.h
@@ -37,9 +37,12 @@
 // actions on double-click on torrents
 enum DoubleClickAction {TOGGLE_PAUSE, OPEN_DEST, NO_ACTION};
 
-class QCloseEvent;
 class AdvancedSettings;
 
+QT_BEGIN_NAMESPACE
+class QCloseEvent;
+QT_END_NAMESPACE
+
 class options_imp : public QDialog, private Ui_Preferences {
   Q_OBJECT
 private:
diff --git a/src/previewselect.h b/src/previewselect.h
index d67960cfd..998f4aa91 100644
--- a/src/previewselect.h
+++ b/src/previewselect.h
@@ -36,9 +36,12 @@
 #include "ui_preview.h"
 #include "qtorrenthandle.h"
 
-class QStandardItemModel;
 class PreviewListDelegate;
 
+QT_BEGIN_NAMESPACE
+class QStandardItemModel;
+QT_END_NAMESPACE
+
 class PreviewSelect: public QDialog, private Ui::preview {
   Q_OBJECT
 
diff --git a/src/properties/peerlistwidget.h b/src/properties/peerlistwidget.h
index 554dd5e4e..511699cf7 100644
--- a/src/properties/peerlistwidget.h
+++ b/src/properties/peerlistwidget.h
@@ -39,13 +39,16 @@
 #include "qtorrenthandle.h"
 #include "misc.h"
 
-class QStandardItemModel;
-class QStandardItem;
-class QSortFilterProxyModel;
 class PeerListDelegate;
 class ReverseResolution;
 class PropertiesWidget;
 
+QT_BEGIN_NAMESPACE
+class QSortFilterProxyModel;
+class QStandardItem;
+class QStandardItemModel;
+QT_END_NAMESPACE
+
 #include <boost/version.hpp>
 #if BOOST_VERSION < 103500
 #include <libtorrent/asio/ip/tcp.hpp>
diff --git a/src/properties/propertieswidget.h b/src/properties/propertieswidget.h
index acb63d9f2..9e656fbd3 100644
--- a/src/properties/propertieswidget.h
+++ b/src/properties/propertieswidget.h
@@ -37,10 +37,8 @@
 
 
 class TransferListWidget;
-class QTimer;
 class TorrentFilesFilterModel;
 class PropListDelegate;
-class QAction;
 class torrent_file;
 class PeerListWidget;
 class TrackerList;
@@ -50,6 +48,11 @@ class PieceAvailabilityBar;
 class PropTabBar;
 class LineEdit;
 
+QT_BEGIN_NAMESPACE
+class QAction;
+class QTimer;
+QT_END_NAMESPACE
+
 class PropertiesWidget : public QWidget, private Ui::PropertiesWidget {
   Q_OBJECT
   Q_DISABLE_COPY(PropertiesWidget)
diff --git a/src/properties/proptabbar.h b/src/properties/proptabbar.h
index 9550512e4..23c1d3774 100644
--- a/src/properties/proptabbar.h
+++ b/src/properties/proptabbar.h
@@ -33,7 +33,9 @@
 
 #include <QHBoxLayout>
 
+QT_BEGIN_NAMESPACE
 class QButtonGroup;
+QT_END_NAMESPACE
 
 class PropTabBar : public QHBoxLayout
 {
diff --git a/src/qtlibtorrent/qbtsession.h b/src/qtlibtorrent/qbtsession.h
index 35059efc3..0d748c92f 100644
--- a/src/qtlibtorrent/qbtsession.h
+++ b/src/qtlibtorrent/qbtsession.h
@@ -53,7 +53,6 @@
 #define MAX_SAMPLES 20
 
 class DownloadThread;
-class QTimer;
 class FilterParserThread;
 class HttpServer;
 class BandwidthScheduler;
diff --git a/src/qtlibtorrent/qtorrenthandle.h b/src/qtlibtorrent/qtorrenthandle.h
index 9b9a8fdf7..6fc1dced7 100644
--- a/src/qtlibtorrent/qtorrenthandle.h
+++ b/src/qtlibtorrent/qtorrenthandle.h
@@ -36,7 +36,10 @@
 #include <libtorrent/torrent_info.hpp>
 
 #include <QString>
+
+QT_BEGIN_NAMESPACE
 class QStringList;
+QT_END_NAMESPACE
 
 // A wrapper for torrent_handle in libtorrent
 // to interact well with Qt types
diff --git a/src/rss/automatedrssdownloader.h b/src/rss/automatedrssdownloader.h
index 1aefb4255..86e434701 100644
--- a/src/rss/automatedrssdownloader.h
+++ b/src/rss/automatedrssdownloader.h
@@ -34,12 +34,17 @@
 #include <QDialog>
 #include "rssdownloadrule.h"
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
 class AutomatedRssDownloader;
 }
+QT_END_NAMESPACE
 
 class RssDownloadRuleList;
+
+QT_BEGIN_NAMESPACE
 class QListWidgetItem;
+QT_END_NAMESPACE
 
 class AutomatedRssDownloader : public QDialog
 {
diff --git a/src/rss/cookiesdlg.h b/src/rss/cookiesdlg.h
index 9f32c936c..3e7469973 100644
--- a/src/rss/cookiesdlg.h
+++ b/src/rss/cookiesdlg.h
@@ -33,9 +33,11 @@
 
 #include <QDialog>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
     class CookiesDlg;
 }
+QT_END_NAMESPACE
 
 class CookiesDlg : public QDialog
 {
diff --git a/src/rss/rss_imp.h b/src/rss/rss_imp.h
index f03e45b1a..fc0aac51d 100644
--- a/src/rss/rss_imp.h
+++ b/src/rss/rss_imp.h
@@ -37,10 +37,13 @@
 #include "ui_rss.h"
 
 class FeedListWidget;
-class QTreeWidgetItem;
 class RssFolder;
 class RssManager;
 
+QT_BEGIN_NAMESPACE
+class QTreeWidgetItem;
+QT_END_NAMESPACE
+
 class RSSImp : public QWidget, public Ui::RSS {
   Q_OBJECT
 
diff --git a/src/rss/rsssettingsdlg.h b/src/rss/rsssettingsdlg.h
index 6027f0f6a..a4d88d177 100644
--- a/src/rss/rsssettingsdlg.h
+++ b/src/rss/rsssettingsdlg.h
@@ -33,9 +33,11 @@
 
 #include <QDialog>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
     class RssSettingsDlg;
 }
+QT_END_NAMESPACE
 
 class RssSettingsDlg : public QDialog
 {
diff --git a/src/searchengine/engineselectdlg.h b/src/searchengine/engineselectdlg.h
index 1e61b54b7..31acdcd47 100644
--- a/src/searchengine/engineselectdlg.h
+++ b/src/searchengine/engineselectdlg.h
@@ -35,7 +35,10 @@
 #include "supportedengines.h"
 
 class DownloadThread;
+
+QT_BEGIN_NAMESPACE
 class QDropEvent;
+QT_END_NAMESPACE
 
 class engineSelectDlg : public QDialog, public Ui::engineSelect{
   Q_OBJECT
diff --git a/src/searchengine/searchengine.h b/src/searchengine/searchengine.h
index 4c9e628f6..3b9629e6c 100644
--- a/src/searchengine/searchengine.h
+++ b/src/searchengine/searchengine.h
@@ -42,10 +42,13 @@
 #include "supportedengines.h"
 
 class DownloadThread;
-class QTimer;
 class SearchEngine;
 class MainWindow;
 
+QT_BEGIN_NAMESPACE
+class QTimer;
+QT_END_NAMESPACE
+
 class SearchEngine : public QWidget, public Ui::search_engine{
   Q_OBJECT
   Q_DISABLE_COPY(SearchEngine)
diff --git a/src/searchengine/searchtab.h b/src/searchengine/searchtab.h
index 16f2dd781..dfc77c2e2 100644
--- a/src/searchengine/searchtab.h
+++ b/src/searchengine/searchtab.h
@@ -38,10 +38,13 @@
 
 class SearchListDelegate;
 class SearchEngine;
+
+QT_BEGIN_NAMESPACE
 class QTreeView;
 class QHeaderView;
 class QStandardItemModel;
 class QSortFilterProxyModel;
+QT_END_NAMESPACE
 
 class SearchTab: public QWidget, public Ui::search_engine {
   Q_OBJECT
diff --git a/src/smtp.h b/src/smtp.h
index a16e05585..8e3cbb456 100644
--- a/src/smtp.h
+++ b/src/smtp.h
@@ -16,9 +16,11 @@
 #include <QObject>
 #include <QByteArray>
 
+QT_BEGIN_NAMESPACE
 struct QTextStream;
 struct QTcpSocket;
 class QTextCodec;
+QT_END_NAMESPACE
 
 class Smtp : public QObject {
   Q_OBJECT
diff --git a/src/torrentimportdlg.h b/src/torrentimportdlg.h
index bc59f58de..e8118b09e 100644
--- a/src/torrentimportdlg.h
+++ b/src/torrentimportdlg.h
@@ -36,9 +36,11 @@
 #include <libtorrent/torrent_info.hpp>
 #include <libtorrent/version.hpp>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
 class TorrentImportDlg;
 }
+QT_END_NAMESPACE
 
 class QBtSession;
 
diff --git a/src/transferlistwidget.h b/src/transferlistwidget.h
index 0da2d83cf..80f55edbd 100644
--- a/src/transferlistwidget.h
+++ b/src/transferlistwidget.h
@@ -35,13 +35,16 @@
 #include <libtorrent/version.hpp>
 #include "qtorrenthandle.h"
 
-class QStandardItemModel;
-class QSortFilterProxyModel;
 class QBtSession;
 class TransferListDelegate;
 class MainWindow;
 class TorrentModel;
 
+QT_BEGIN_NAMESPACE
+class QSortFilterProxyModel;
+class QStandardItemModel;
+QT_END_NAMESPACE
+
 enum TorrentFilter {FILTER_ALL, FILTER_DOWNLOADING, FILTER_COMPLETED, FILTER_PAUSED, FILTER_ACTIVE, FILTER_INACTIVE};
 
 class TransferListWidget: public QTreeView {
diff --git a/src/webui/httpconnection.h b/src/webui/httpconnection.h
index e5878e80f..8c1f34dba 100644
--- a/src/webui/httpconnection.h
+++ b/src/webui/httpconnection.h
@@ -36,9 +36,12 @@
 #include "httpresponsegenerator.h"
 #include <QObject>
 
-class QTcpSocket;
 class HttpServer;
 
+QT_BEGIN_NAMESPACE
+class QTcpSocket;
+QT_END_NAMESPACE
+
 class HttpConnection : public QObject
 {
   Q_OBJECT
diff --git a/src/webui/httpserver.h b/src/webui/httpserver.h
index d93dd00b7..b8886d67f 100644
--- a/src/webui/httpserver.h
+++ b/src/webui/httpserver.h
@@ -38,9 +38,12 @@
 #include <QHash>
 #include "preferences.h"
 
-class QTimer;
 class EventManager;
 
+QT_BEGIN_NAMESPACE
+class QTimer;
+QT_END_NAMESPACE
+
 const int MAX_AUTH_FAILED_ATTEMPTS = 5;
 
 class HttpServer : public QTcpServer {