diff --git a/Hv2ray.pro b/Hv2ray.pro
index 48af9e0d..8afcaefa 100644
--- a/Hv2ray.pro
+++ b/Hv2ray.pro
@@ -34,7 +34,8 @@ SOURCES += \
     vinteract.cpp \
     db.cpp \
     vmess.cpp \
-    utils.cpp
+    utils.cpp \
+    src/runguard.cpp
 
 HEADERS += \
         mainwindow.h \
@@ -43,7 +44,8 @@ HEADERS += \
     vinteract.h \
     db.h \
     vmess.h \
-    utils.h
+    utils.h \
+    src/runguard.h
 
 FORMS += \
         mainwindow.ui \
diff --git a/src/main.cpp b/src/main.cpp
index 84f7add5..b9c68a5d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -8,7 +8,8 @@
 #include <QSqlQuery>
 #include <QSqlError>
 #include <QFileInfo>
-
+#include <QMessageBox>
+#include "runguard.h"
 
 void init()
 {
@@ -40,6 +41,11 @@ void init()
 int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);
+    RunGuard guard("Hv2ray");
+    if(!guard.tryToRun()) {
+        QMessageBox::critical(0, "Already running", "Another instance of Hv2ray is already running!", QMessageBox::Ok | QMessageBox::Default);
+        return 0;
+    }
     init();
     MainWindow w;
     w.show();
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 9bbe52dc..c1df4c12 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -17,6 +17,7 @@ MainWindow::MainWindow(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::MainWindow)
 {
+    this->setWindowIcon(QIcon("Himeki.ico"));
     ui->setupUi(this);
     updateConfTable();
     ui->configTable->setContextMenuPolicy(Qt::CustomContextMenu);
diff --git a/src/runguard.cpp b/src/runguard.cpp
new file mode 100644
index 00000000..a7c007df
--- /dev/null
+++ b/src/runguard.cpp
@@ -0,0 +1,76 @@
+#include "runguard.h"
+#include <QCryptographicHash>
+
+//from https://stackoverflow.com/a/28172162
+namespace
+{
+
+    QString generateKeyHash( const QString& key, const QString& salt )
+    {
+        QByteArray data;
+        data.append( key.toUtf8() );
+        data.append( salt.toUtf8() );
+        data = QCryptographicHash::hash( data, QCryptographicHash::Sha1 ).toHex();
+        return data;
+    }
+
+}
+
+
+RunGuard::RunGuard( const QString& key )
+    : key( key )
+    , memLockKey( generateKeyHash( key, "_memLockKey" ) )
+    , sharedmemKey( generateKeyHash( key, "_sharedmemKey" ) )
+    , sharedMem( sharedmemKey )
+    , memLock( memLockKey, 1 )
+{
+    memLock.acquire();
+    {
+        QSharedMemory fix( sharedmemKey );    // Fix for *nix: http://habrahabr.ru/post/173281/
+        fix.attach();
+    }
+    memLock.release();
+}
+
+RunGuard::~RunGuard()
+{
+    release();
+}
+
+bool RunGuard::isAnotherRunning()
+{
+    if ( sharedMem.isAttached() ) {
+        return false;
+    }
+    memLock.acquire();
+    const bool isRunning = sharedMem.attach();
+    if ( isRunning ) {
+        sharedMem.detach();
+    }
+    memLock.release();
+    return isRunning;
+}
+
+bool RunGuard::tryToRun()
+{
+    if ( isAnotherRunning() ) { // Extra check
+        return false;
+    }
+    memLock.acquire();
+    const bool result = sharedMem.create( sizeof( quint64 ) );
+    memLock.release();
+    if ( !result ) {
+        release();
+        return false;
+    }
+    return true;
+}
+
+void RunGuard::release()
+{
+    memLock.acquire();
+    if ( sharedMem.isAttached() ) {
+        sharedMem.detach();
+    }
+    memLock.release();
+}
diff --git a/src/runguard.h b/src/runguard.h
new file mode 100644
index 00000000..555318b5
--- /dev/null
+++ b/src/runguard.h
@@ -0,0 +1,31 @@
+#ifndef RUNGUARD_H
+#define RUNGUARD_H
+
+#include <QObject>
+#include <QSharedMemory>
+#include <QSystemSemaphore>
+
+//from https://stackoverflow.com/a/28172162
+class RunGuard
+{
+
+public:
+    RunGuard( const QString& key );
+    ~RunGuard();
+
+    bool isAnotherRunning();
+    bool tryToRun();
+    void release();
+
+private:
+    const QString key;
+    const QString memLockKey;
+    const QString sharedmemKey;
+
+    QSharedMemory sharedMem;
+    QSystemSemaphore memLock;
+
+    Q_DISABLE_COPY( RunGuard )
+};
+
+#endif // RUNGUARD_H