diff --git a/src/scalepicker.h b/src/scalepicker.h
--- a/src/scalepicker.h
+++ b/src/scalepicker.h
@@ -25,6 +25,7 @@
 #include <QPen>
 #include <QWidget>
 #include <QList>
+#include <QMap>
 #include <qwt_scale_widget.h>
 #include <qwt_widget_overlay.h>
 
@@ -58,17 +59,20 @@ private:
     double firstPosPx; // pixel coordinates
     double currentPosPx; // current position in pixel coordinates
     QList<int> snapPoints;
+    /// used to restore precision of snappoints that is lost due to rounding
+    QMap<int, double> snapPointMap;
 
-    double position(double); // returns the axis mouse position relative to plot coordinates
+    double position(double) const; // returns the axis mouse position relative to plot coordinates
     int positionPx(QMouseEvent*); // returns the axis mouse position in pixels
     double posCanvasPx(double pos) const; // returns the given position in canvas coordinates
     void drawTriangle(QPainter* painter, int position);
-
-private slots:
-    /// Returns tracker text position
+    QwtText trackerText() const;
+     /// Returns tracker text position
     QRectF trackerTextRect(QPainter* painter, int posPx, QSizeF textSize) const;
     /// Returns the text position for tracker text shown during picking
     QRectF pickTrackerTextRect(QPainter* painter, QRect pickRect, QSizeF textSize) const;
+
+private slots:
     void updateSnapPoints();
 };