Invalid convert to auto-property gets suggested

Given the following:

        private RectangleF _someRectangle;        
        public RectangleF SomeRectangle
        {             get { return _someRectangle; }         }

ReSharper will suggest that this can be converted to an auto-property with a private setter. However later in the code the fields of the rectangle are updated

            _someRectangle.X = some_value;         
            _someRectangle.Width = some_other_value;
and that becomes

            SomeRectangle.X = some_value;
            SomeRectangle.Width = some_other_value;

Which results in a "Cannot modify the return value of  '...SomeRectangle' because it is not a variable".

How do I turn off the suggestion for specific instances? Unlike other options the context menu doesn't provide a way to comment out this suggestion.