String concatenation in VBA

I have a formula (without the preceding = sign) in a cell, and I want to copy it to a diff cell and add the preceding = sign. I need to do this in a macro and I also have to use absolute numbers of the cells and not relativ开发者_开发知识库e references. How do I do it?

With ThisWorkbook.Sheets("Sheet1")
  .Range("A1").Formula = "=" & .Range("B1").Value
End With