diff --git a/ch.psi.plot/src/main/java/ch/psi/plot/MatrixPlotBase.java b/ch.psi.plot/src/main/java/ch/psi/plot/MatrixPlotBase.java
index 19bc126..45193e8 100644
--- a/ch.psi.plot/src/main/java/ch/psi/plot/MatrixPlotBase.java
+++ b/ch.psi.plot/src/main/java/ch/psi/plot/MatrixPlotBase.java
@@ -52,8 +52,9 @@ abstract public class MatrixPlotBase extends PlotBase<MatrixPlotSeries> implemen
             if ((series == null) || (getNumberOfSeries() == 0)) {
                 return;
             }
-            final int indexX = ((int) ((x - series.getMinX()) / series.getBinWidthX()));
-            final int indexY = ((int) ((y - series.getMinY()) / series.getBinWidthY()));
+            final int indexX = (int)Math.round((x - series.getMinX()) / series.getBinWidthX());
+            final int indexY = (int)Math.round((y - series.getMinY()) / series.getBinWidthY());
+            
             if (!series.contains(indexX, indexY)) {
                 return;
             }