How do you add a column to a univariate zoo series?

Suppose I have a univariate zoo series:

v <- read.zoo(data.frame(dt=c(as.Date('2019-01-01')+1:10), vals=1:10))
v
2019-01-02 2019-01-03 2019-01-04 2019-01-05 2019-01-06 2019-01-07 2019-01-08 2019-01-09 2019-01-10 2019-01-11 
         1          2          3          4          5          6          7          8          9         10 

I would like to turn this into a regular zoo series with an additional column val2 which has let's say "test":

           val  val2
2019-01-02  1     test
2019-01-03  2     test
...

I tried the following. It logically shouldn't work (since the zoo object is univariate) but I figured since this works for a data.frame it might work or I'd get an error or warning to guide me towards the right path which surprisingly didn't happen but it did something REALLY BAD...:

   cbind(v, val2="test")
               v    val2
    1970-01-02 <NA> test
    2019-01-02 1    <NA>
    2019-01-03 2    <NA>
    2019-01-04 3    <NA>
    2019-01-05 4    <NA>
    2019-01-06 5    <NA>
    2019-01-07 6    <NA>
    2019-01-08 7    <NA>
    2019-01-09 8    <NA>
    2019-01-10 9    <NA>
    2019-01-11 10   <NA>

I would have expected it to fill val2 with the value: "test" or give me some warnings/errors.