diff --git a/src/main.cpp b/src/main.cpp
index a1912fb48..809e3a084 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -75,6 +75,10 @@ Q_IMPORT_PLUGIN(qico)
 #include "misc.h"
 #include "preferences.h"
 
+#if defined(Q_OS_WIN) && !defined(QBT_HAS_GETCURRENTPID)
+#error You seem to have updated QtSingleApplication without porting our custom QtSingleApplication::getRunningPid() function. Please see previous version to understate how it works.
+#endif
+
 class UsageDisplay: public QObject {
   Q_OBJECT
 
@@ -207,7 +211,7 @@ int main(int argc, char *argv[]) {
     qDebug("qBittorrent is already running for this user.");
     // Read torrents given on command line
 #ifdef Q_OS_WIN
-    DWORD pid = app.getRunningPid();
+    DWORD pid = (DWORD)app.getRunningPid();
     if (pid > 0) {
       BOOL b = AllowSetForegroundWindow(pid);
       qDebug("AllowSetForegroundWindow() returns %s", b ? "TRUE" : "FALSE");
diff --git a/src/qtsingleapp/qtlocalpeer.cpp b/src/qtsingleapp/qtlocalpeer.cpp
index fcf2d4a83..fe770c6e1 100644
--- a/src/qtsingleapp/qtlocalpeer.cpp
+++ b/src/qtsingleapp/qtlocalpeer.cpp
@@ -202,10 +202,12 @@ void QtLocalPeer::receiveConnection()
     }
     QString message(QString::fromUtf8(uMsg));
 #ifdef Q_OS_WIN
-    if (message == "qbt://pid")
-      socket->write(QByteArray::number(qApp->applicationPid()));
-    else
+    if (message == "qbt://pid") {
+      qint64 pid = GetCurrentProcessId();
+      socket->write((const char *)&pid, sizeof pid);
+    } else {
       socket->write(ack, qstrlen(ack));
+    }
 #else
     socket->write(ack, qstrlen(ack));
 #endif
@@ -219,9 +221,9 @@ void QtLocalPeer::receiveConnection()
 }
 
 #ifdef Q_OS_WIN
-ulong QtLocalPeer::getRunningPid() {
+qint64 QtLocalPeer::getRunningPid() {
   if (!isClient())
-      return false;
+      return 0;
 
   QLocalSocket socket;
   bool connOk = false;
@@ -231,32 +233,23 @@ ulong QtLocalPeer::getRunningPid() {
       connOk = socket.waitForConnected(5000/2);
       if (connOk || i)
           break;
-      Sleep(DWORD(250));
+      Sleep(250);
   }
-  if (!connOk)
-      return false;
-  QByteArray uMsg("qbt://pid");
+  if (!connOk) return -1;
+
+  const char* msg = "qbt://pid";
   QDataStream ds(&socket);
-  ds.writeBytes(uMsg.constData(), uMsg.size());
-  bool res = socket.waitForBytesWritten(5000);
-  res &= socket.waitForReadyRead(5000);
-  if (!res)
-    return -1;
-  while (socket.bytesAvailable() < (int)sizeof(quint32))
+  ds.writeBytes(msg, qstrlen(msg));
+  bool res = socket.waitForBytesWritten(5000) && socket.waitForReadyRead(5000);
+  if (!res) return -1;
+
+  DWORD pid;
+  qint64 pid_size = sizeof pid;
+  while (socket.bytesAvailable() < pid_size)
       socket.waitForReadyRead();
-  uMsg.clear();
-  quint32 remaining = socket.bytesAvailable();
-  uMsg.resize(remaining);
-  int got = 0;
-  char* uMsgBuf = uMsg.data();
-  do {
-      got = ds.readRawData(uMsgBuf, remaining);
-      remaining -= got;
-      uMsgBuf += got;
-  } while (remaining && got >= 0 && socket.waitForReadyRead(2000));
-  if (got < 0)
-    return -1;
+  if (socket.read((char *)&pid, pid_size) < pid_size)
+      return -1;
 
-  return uMsg.toULong();
+  return pid;
 }
 #endif
diff --git a/src/qtsingleapp/qtlocalpeer.h b/src/qtsingleapp/qtlocalpeer.h
index 3a6d46959..2fa091f3f 100644
--- a/src/qtsingleapp/qtlocalpeer.h
+++ b/src/qtsingleapp/qtlocalpeer.h
@@ -65,7 +65,7 @@ public:
     QString applicationId() const
         { return id; }
 #ifdef Q_OS_WIN
-    ulong getRunningPid();
+    qint64 getRunningPid();
 #endif
 
 Q_SIGNALS:
diff --git a/src/qtsingleapp/qtsingleapplication.cpp b/src/qtsingleapp/qtsingleapplication.cpp
index fa0b0b6a6..c3b894348 100644
--- a/src/qtsingleapp/qtsingleapplication.cpp
+++ b/src/qtsingleapp/qtsingleapplication.cpp
@@ -351,7 +351,7 @@ void QtSingleApplication::activateWindow()
 */
 
 #ifdef Q_OS_WIN
-ulong QtSingleApplication::getRunningPid() {
+qint64 QtSingleApplication::getRunningPid() {
   return peer->getRunningPid();
 }
 #endif
diff --git a/src/qtsingleapp/qtsingleapplication.h b/src/qtsingleapp/qtsingleapplication.h
index e45e373c9..0ffd8f6ee 100644
--- a/src/qtsingleapp/qtsingleapplication.h
+++ b/src/qtsingleapp/qtsingleapplication.h
@@ -89,7 +89,8 @@ public:
     void initialize(bool dummy = true)
         { isRunning(); Q_UNUSED(dummy) }
 #ifdef Q_OS_WIN
-    ulong getRunningPid();
+#define QBT_HAS_GETCURRENTPID
+    qint64 getRunningPid();
 #endif
 
 public Q_SLOTS: