diff --git a/CHANGES.rst b/CHANGES.rst
index 2d78af8c..f94bd687 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -101,6 +101,8 @@ Changes in this release include the following:
 
 
 
+* Detach wxControl in AuiToolbar from current sizer before attach to a new one.
+  (#843)
 
 4.0.1 "Lemonade"
 ----------------
diff --git a/wx/lib/agw/aui/auibar.py b/wx/lib/agw/aui/auibar.py
index d199d77c..af61dc72 100644
--- a/wx/lib/agw/aui/auibar.py
+++ b/wx/lib/agw/aui/auibar.py
@@ -3072,6 +3072,9 @@ class AuiToolBar(wx.Control):
                     sizer_item = sizer.Add((item.spacer_pixels, 1))
 
             elif kind == ITEM_CONTROL:
+                if item.window and item.window.GetContainingSizer():
+                    # Make sure that there is only one sizer to this control
+                    item.window.GetContainingSizer().Detach(item.window);
 
                 vert_sizer = wx.BoxSizer(wx.VERTICAL)
                 vert_sizer.AddStretchSpacer(1)