diff --git a/map65/plotter.cpp b/map65/plotter.cpp
index 245264dd3..20b0f81b6 100644
--- a/map65/plotter.cpp
+++ b/map65/plotter.cpp
@@ -16,6 +16,7 @@ CPlotter::CPlotter(QWidget *parent) :                  //CPlotter Constructor
   setAutoFillBackground(false);
   setAttribute(Qt::WA_OpaquePaintEvent, false);
   setAttribute(Qt::WA_NoSystemBackground, true);
+  setMouseTracking(true);
 
   m_StartFreq = 100;
   m_nSpan=65;                    //Units: kHz
@@ -763,6 +764,23 @@ void CPlotter::setLockTxRx(bool b)
   }
 }
 
+void CPlotter::mouseMoveEvent (QMouseEvent * event)
+{
+  int h = m_WaterfallPixmap.height();
+  int x=event->x();
+  int y=event->y();
+  bool lower=(y > 30+h);
+  float freq=FreqfromX(x);
+  float df=m_fSample/32768.0;
+  int ndf=x*df + m_ZoomStartFreq;
+  if(lower) {
+    QToolTip::showText(event->globalPos(),QString::number(ndf));
+  } else {
+    QToolTip::showText(event->globalPos(),QString::number(freq));
+  }
+  QWidget::mouseMoveEvent(event);
+}
+
 double CPlotter::rxFreq()
 {
   return floor(datcom_.fcenter) + 0.001*m_fQSO + 0.000001*m_DF;
diff --git a/map65/plotter.h b/map65/plotter.h
index 2d372c6c6..6f2922458 100644
--- a/map65/plotter.h
+++ b/map65/plotter.h
@@ -10,6 +10,7 @@
 #include <QtGui>
 #include <QFrame>
 #include <QImage>
+#include <QToolTip>
 #include <cstring>
 #include "commons.h"
 
@@ -82,6 +83,7 @@ protected:
   //re-implemented widget event handlers
   void paintEvent(QPaintEvent *event);
   void resizeEvent(QResizeEvent* event);
+  void mouseMoveEvent(QMouseEvent * event) override;
 
 private: