Argument `needs_dots` in R (tibble)

Since a while ago tibble is throwing warning messages (although the outputs are correct). The only thing I remember changing before it had started was re-installing pandoc. If I keep data in data.frame, there is no such warning. This is how the message looks like. How do I fix it?

df <- data.frame('A' = c(1, 2), 'B' = c('a', 'b'))
df

> df
  A B
1 1 a
2 2 b

tibble::as_tibble(df)

# A tibble: 2 x 2
      A B    
  <dbl> <chr>
1     1 a    
2     2 b 

Warning message:
`...` is not empty.

'We detected these problematic arguments:
* `needs_dots`'

These dots only exist to allow future extensions and should be empty.
Did you misspecify an argument?