diff --git a/include/osgViewer/api/X11/GraphicsWindowX11 b/include/osgViewer/api/X11/GraphicsWindowX11
index f226300e4..6c3e69555 100644
--- a/include/osgViewer/api/X11/GraphicsWindowX11
+++ b/include/osgViewer/api/X11/GraphicsWindowX11
@@ -166,6 +166,7 @@ class OSGVIEWER_EXPORT GraphicsWindowX11 : public osgViewer::GraphicsWindow
         void forceKey(int key, double time, bool state);
         void getModifierMap(char* keymap) const;
         int getModifierMask() const;
+        void syncCapsLock();
         
         bool            _valid;
         Display*        _display;
diff --git a/src/osgViewer/GraphicsWindowX11.cpp b/src/osgViewer/GraphicsWindowX11.cpp
index 11bd12c48..46e418874 100644
--- a/src/osgViewer/GraphicsWindowX11.cpp
+++ b/src/osgViewer/GraphicsWindowX11.cpp
@@ -1018,6 +1018,7 @@ void GraphicsWindowX11::checkEvents()
             case EnterNotify :
                 osg::notify(osg::INFO)<<"EnterNotify event received"<<std::endl;
                 _lockMask = ev.xcrossing.state & LockMask;
+                syncCapsLock();
                 break;
 
             case KeymapNotify :
@@ -1030,6 +1031,7 @@ void GraphicsWindowX11::checkEvents()
 
                 char modMap[32];
                 getModifierMap(modMap);
+                syncCapsLock();
 
                 // release normal (non-modifier) keys
                 for (unsigned int key = 8; key < 256; key++)
@@ -1340,6 +1342,20 @@ void GraphicsWindowX11::forceKey(int key, double time, bool state)
     }
 }
 
+void GraphicsWindowX11::syncCapsLock()
+{
+    unsigned int mask = getEventQueue()->getCurrentEventState()->getModKeyMask();
+    if (_lockMask)
+    {
+        mask |= osgGA::GUIEventAdapter::MODKEY_CAPS_LOCK;
+    }
+    else
+    {
+        mask &= ~osgGA::GUIEventAdapter::MODKEY_CAPS_LOCK;
+    }
+    getEventQueue()->getCurrentEventState()->setModKeyMask(mask);
+}
+
 // Returns char[32] keymap with bits for every modifier key set.
 void GraphicsWindowX11::getModifierMap(char* keymap) const
 {