Join 2 Cells In VBA

I'm writing an Excel Macro and want to sum a number cell with the value "45667" and a text cell with the value "Prague" and return it to a new cell with the value " 45667 Prague"

I've done it successfully with the two text cells "John" and "Hopkins" to "John Hopkins".

This is my

Sub SumCells()

Dim FirstName, SecondName, Zipcode, City, fullname, fulladdres, space

FirstName = range("cell1").value
SecondName = range("cell2").value
Zipcode = range("cell3").value
City = range("cell4").value
space = " "

fullname = firstname + space + secondname
fulladdress = zipcode + space + city

The problem is that city is recognized as "Prague", and the zipcode as 45667 (without the "")