VBA Inserts "NM" instead of 0""

So I macro that should grab the existing cell formula and then wrap it with an iferror, but instead of inserting a 0 into the iferror formula it inserts "NM".

Sub InsertIfError()
'
' InsertIfError Macro
'
' Keyboard Shortcut: Ctrl+Shift+E
'
Dim c As Range
    
    For Each c In Selection
        c.forumla = "=iferror(" & c.Formula & ", 0 )"
    Next c
    
End Sub

For example if the cell formula is "=A1+B1" and I run the macro it will insert "=iferror(A1+B1,"NM")"