diff --git a/src/PositionManager/PositionManager.cpp b/src/PositionManager/PositionManager.cpp
index 88c4e25200d4991d4cdafd853d70603ed920ca56..5de73d0f6e715a455e19de612c91dfbc486469e6 100644
--- a/src/PositionManager/PositionManager.cpp
+++ b/src/PositionManager/PositionManager.cpp
@@ -50,8 +50,19 @@ void QGCPositionManager::setToolbox(QGCToolbox *toolbox)
 
 void QGCPositionManager::setNmeaSourceDevice(QIODevice* device)
 {
+    // stop and release _nmeaSource
     if (_nmeaSource) {
+        _nmeaSource->stopUpdates();
+        disconnect(_nmeaSource);
+
+        // if _currentSource is pointing there, point to null
+        if (_currentSource == _nmeaSource){
+            _currentSource = nullptr;
+        }
+
         delete _nmeaSource;
+        _nmeaSource = nullptr;
+
     }
     _nmeaSource = new QNmeaPositionInfoSource(QNmeaPositionInfoSource::RealTimeMode, this);
     _nmeaSource->setDevice(device);