diff --git a/src/Mod/Path/PathScripts/PathAreaOp.py b/src/Mod/Path/PathScripts/PathAreaOp.py
index 8ba0b9ae1b..5053372c85 100644
--- a/src/Mod/Path/PathScripts/PathAreaOp.py
+++ b/src/Mod/Path/PathScripts/PathAreaOp.py
@@ -276,34 +276,9 @@ class ObjectOp(object):
         baselist = obj.Base
         if baselist is None:
             baselist = []
-        if len(baselist) == 0:  # When adding the first base object, guess at heights
-
-            try:
-                bb = base.Shape.BoundBox  # parent boundbox
-                subobj = base.Shape.getElement(sub)
-                fbb = subobj.BoundBox  # feature boundbox
-                obj.StartDepth = bb.ZMax
-                obj.ClearanceHeight = bb.ZMax + 5.0
-                obj.SafeHeight = bb.ZMax + 3.0
-
-                if fbb.ZMax == fbb.ZMin and fbb.ZMax == bb.ZMax:  # top face
-                    obj.FinalDepth = bb.ZMin
-                elif fbb.ZMax > fbb.ZMin and fbb.ZMax == bb.ZMax:  # vertical face, full cut
-                    obj.FinalDepth = fbb.ZMin
-                elif fbb.ZMax > fbb.ZMin and fbb.ZMin > bb.ZMin:  # internal vertical wall
-                    obj.FinalDepth = fbb.ZMin
-                elif fbb.ZMax == fbb.ZMin and fbb.ZMax > bb.ZMin:  # face/shelf
-                    obj.FinalDepth = fbb.ZMin
-                else:  # catch all
-                    obj.FinalDepth = bb.ZMin
-            except:
-                obj.StartDepth = 5.0
-                obj.ClearanceHeight = 10.0
-                obj.SafeHeight = 8.0
-
         item = (base, sub)
         if item in baselist:
             PathLog.warning(translate("Path", "this object already in the list" + "\n"))
         else:
             baselist.append(item)
-        obj.Base = baselist
+            obj.Base = baselist
diff --git a/src/Mod/Path/PathScripts/PathPocket.py b/src/Mod/Path/PathScripts/PathPocket.py
index 71ab3dd1b5..63057ba240 100644
--- a/src/Mod/Path/PathScripts/PathPocket.py
+++ b/src/Mod/Path/PathScripts/PathPocket.py
@@ -168,6 +168,31 @@ class ObjectPocket(PathAreaOp.ObjectOp):
         obj.StepOver = 100
         obj.ZigZagAngle = 45
 
+    def opOnChanged(self, obj, prop):
+        if prop == 'Base' and len(obj.Base) == 1:
+            try:
+                bb = base.Shape.BoundBox  # parent boundbox
+                subobj = base.Shape.getElement(sub)
+                fbb = subobj.BoundBox  # feature boundbox
+                obj.StartDepth = bb.ZMax
+                obj.ClearanceHeight = bb.ZMax + 5.0
+                obj.SafeHeight = bb.ZMax + 3.0
+
+                if fbb.ZMax == fbb.ZMin and fbb.ZMax == bb.ZMax:  # top face
+                    obj.FinalDepth = bb.ZMin
+                elif fbb.ZMax > fbb.ZMin and fbb.ZMax == bb.ZMax:  # vertical face, full cut
+                    obj.FinalDepth = fbb.ZMin
+                elif fbb.ZMax > fbb.ZMin and fbb.ZMin > bb.ZMin:  # internal vertical wall
+                    obj.FinalDepth = fbb.ZMin
+                elif fbb.ZMax == fbb.ZMin and fbb.ZMax > bb.ZMin:  # face/shelf
+                    obj.FinalDepth = fbb.ZMin
+                else:  # catch all
+                    obj.FinalDepth = bb.ZMin
+            except:
+                obj.StartDepth = 5.0
+                obj.ClearanceHeight = 10.0
+                obj.SafeHeight = 8.0
+
 
 def Create(name):
     obj = FreeCAD.ActiveDocument.addObject("Path::FeaturePython", name)