Index: trunk/src/org/openstreetmap/josm/actions/ZoomInAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/ZoomInAction.java	(revision 4492)
+++ trunk/src/org/openstreetmap/josm/actions/ZoomInAction.java	(revision 4494)
@@ -30,5 +30,5 @@
     public void actionPerformed(ActionEvent e) {
         if (!Main.isDisplayingMapView()) return;
-        Main.map.mapView.zoomToFactor(0.9);
+        Main.map.mapView.zoomToFactor(1/Math.sqrt(2));
     }
 
Index: trunk/src/org/openstreetmap/josm/actions/ZoomOutAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/ZoomOutAction.java	(revision 4492)
+++ trunk/src/org/openstreetmap/josm/actions/ZoomOutAction.java	(revision 4494)
@@ -25,5 +25,5 @@
     public void actionPerformed(ActionEvent e) {
         if (!Main.isDisplayingMapView()) return;
-        Main.map.mapView.zoomToFactor(1/0.9);
+        Main.map.mapView.zoomToFactor(Math.sqrt(2));
     }
 
Index: trunk/src/org/openstreetmap/josm/gui/MapMover.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MapMover.java	(revision 4492)
+++ trunk/src/org/openstreetmap/josm/gui/MapMover.java	(revision 4494)
@@ -182,5 +182,5 @@
      */
     public void mouseWheelMoved(MouseWheelEvent e) {
-        nc.zoomToFactor(e.getX(), e.getY(), Math.pow(0.8, - e.getWheelRotation()));
+        nc.zoomToFactor(e.getX(), e.getY(), Math.pow(Math.sqrt(2), e.getWheelRotation()));
     }