diff --git a/dummygrid.c b/dummygrid.c
index 42025e0..6131e13 100644
--- a/dummygrid.c
+++ b/dummygrid.c
@@ -11,6 +11,13 @@ cDummyGrid::cDummyGrid(cChannelColumn *c, time_t start, time_t end) : cGrid(c) {
 cDummyGrid::~cDummyGrid(void) {
 }
 
+time_t cDummyGrid::Duration(void) { 
+    //max Duration 5h
+    if (end - start > 18000)
+        return 18000;
+    return (end - start); 
+};
+
 void cDummyGrid::SetViewportHeight() {
     int viewportHeightOld = viewportHeight;
     viewportHeight = Duration() / 60 * tvguideConfig.minutePixel;
diff --git a/dummygrid.h b/dummygrid.h
index 0f6565a..22d4113 100644
--- a/dummygrid.h
+++ b/dummygrid.h
@@ -9,7 +9,7 @@ private:
     time_t end;
     cString strText;
     void drawText();
-    time_t Duration(void) { return (end - start); };
+    time_t Duration(void);
 public:
     cDummyGrid(cChannelColumn *c, time_t start, time_t end);
     virtual ~cDummyGrid(void);