diff --git a/src/osgGA/NodeTrackerManipulator.cpp b/src/osgGA/NodeTrackerManipulator.cpp
index a5e7056d7..266262d7e 100644
--- a/src/osgGA/NodeTrackerManipulator.cpp
+++ b/src/osgGA/NodeTrackerManipulator.cpp
@@ -212,7 +212,7 @@ bool NodeTrackerManipulator::handle(const GUIEventAdapter& ea,GUIActionAdapter&
             if (ea.getButtonMask()==0)
             {
 
-                double timeSinceLastRecordEvent = ea.getTime() - _ga_t0->getTime();
+                double timeSinceLastRecordEvent = _ga_t0.valid() ? (ea.getTime() - _ga_t0->getTime()) : DBL_MAX;
                 if (timeSinceLastRecordEvent>0.02) addMouseEvent(ea);
 
                 if (isMouseMoving())
diff --git a/src/osgGA/TrackballManipulator.cpp b/src/osgGA/TrackballManipulator.cpp
index 4aac40e53..ac0deb0ea 100644
--- a/src/osgGA/TrackballManipulator.cpp
+++ b/src/osgGA/TrackballManipulator.cpp
@@ -107,7 +107,7 @@ bool TrackballManipulator::handle(const GUIEventAdapter& ea,GUIActionAdapter& us
             if (ea.getButtonMask()==0)
             {
             
-                double timeSinceLastRecordEvent = ea.getTime() - _ga_t0->getTime();
+                double timeSinceLastRecordEvent = _ga_t0.valid() ? (ea.getTime() - _ga_t0->getTime()) : DBL_MAX;
                 if (timeSinceLastRecordEvent>0.02) addMouseEvent(ea);
 
                 if (isMouseMoving())