diff --git a/lcl/forms.pp b/lcl/forms.pp
index 8da2a35dbc..cafc46077d 100644
--- a/lcl/forms.pp
+++ b/lcl/forms.pp
@@ -180,6 +180,7 @@ type
     function AutoScrollEnabled: Boolean; virtual;
     procedure CalculateAutoRanges; virtual;
     procedure CreateWnd; override;
+    procedure DestroyWnd; override;
     function GetClientScrollOffset: TPoint; override;
     function GetLogicalClientRect: TRect; override;// logical size of client area
     procedure DoOnResize; override;
diff --git a/lcl/include/custommemo.inc b/lcl/include/custommemo.inc
index f967663c7a..f8b65162db 100644
--- a/lcl/include/custommemo.inc
+++ b/lcl/include/custommemo.inc
@@ -142,6 +142,8 @@ begin
     DebugLn('[TCustomMemo.FinalizeWnd] END ',DbgSName(Self),' ',FLines.ClassName,' FLines.Count=',dbgs(FLines.Count));
     {$endif}
   end;
+  if FHorzScrollBar <> nil then FHorzScrollBar.InvalidateScrollInfo;
+  if FVertScrollBar <> nil then FVertScrollBar.InvalidateScrollInfo;
   inherited FinalizeWnd;
 end;
 
diff --git a/lcl/include/scrollingwincontrol.inc b/lcl/include/scrollingwincontrol.inc
index fd62d5c128..3461d7f07a 100644
--- a/lcl/include/scrollingwincontrol.inc
+++ b/lcl/include/scrollingwincontrol.inc
@@ -35,6 +35,13 @@ begin
   end;
 end;
 
+procedure TScrollingWinControl.DestroyWnd;
+begin
+  inherited DestroyWnd;
+  if FHorzScrollBar <> nil then FHorzScrollBar.InvalidateScrollInfo;
+  if FVertScrollBar <> nil then FVertScrollBar.InvalidateScrollInfo;
+end;
+
 function TScrollingWinControl.GetClientScrollOffset: TPoint;
 begin
   if (HorzScrollBar <> nil) and (VertScrollBar <> nil) then
@@ -75,8 +82,7 @@ begin
   //debugln(['TScrollingWinControl.DoOnResize ',DbgSName(Self),' ',dbgs(BoundsRect),' ',dbgs(ClientRect),' ',dbgs(GetLogicalClientRect)]);
 end;
 
-procedure TScrollingWinControl.GetPreferredSizeClientFrame(out aWidth,
-  aHeight: integer);
+procedure TScrollingWinControl.GetPreferredSizeClientFrame(out aWidth, aHeight: Integer);
 // return frame width independent of scrollbars (i.e. as if scrollbars not shown)
 begin
   if AutoScroll and (VertScrollBar<>nil) then