diff --git a/lcl/controls.pp b/lcl/controls.pp
index 9de16830af..c9aef94078 100644
--- a/lcl/controls.pp
+++ b/lcl/controls.pp
@@ -3587,7 +3587,7 @@ begin
           if Kind in [akLeft,akRight] then begin
             // center horizontally
             if ReferenceControl=OwnerParent then
-              Position:=GetParentSidePos(akRight)-GetParentSidePos(akLeft)
+              Position:=(GetParentSidePos(akRight)+GetParentSidePos(akLeft)) div 2
             else
               Position:=ReferenceControl.Left+(ReferenceControl.Width div 2);
             if Kind=akLeft then