Alter Looping In VBA

Starting at cell H4 and down, I have data pasted to whatever last row, this is a helper sheet/vba thing that helps to create the Case Statement for SQL queries, we have many of them, broken into Pages. So this works great, grabs the data and puts 'data','data2'

The only thing is that in the last data cell in the loop, it leaves off an extra comma, as in:

'306','307','308','309','310','311','312',

I need help in removing that extra comma if there is nothing left to process in the loop so it would look like this:

'306','307','308','309','310','311','312'

Sub Test_Range_Loop()

Dim x As Variant
Dim rng As Range, cel As Range
Dim lr As Long

lr = ActiveSheet.Range("H" & ActiveSheet.Rows.Count).End(xlUp).Row ' find the last row from the bottom-up using H

With ActiveSheet
Set rng = .Range("H4:H" & lr)
For Each cel In rng
x = x & "'" & cel.Value & "',"
Next
.Range("I1").Value = x
End With
End Sub