Use ifelse inside case_when as function

Question

I want to put ifelse opart inside dplyr case_when function:

library(mutate)

data(mtcars)

mtcars %>% 
  dplyr::mutate(myVar = case_when(
    mpg > 20 ~ ifelse(cyl == 6, 1, NA_real_),
    TRUE ~ 2
  ))

into it's own function:

myFun <- function(x) {
  ifelse(cyl == x, 1, NA_real_)
}

mtcars %>% 
  dplyr::mutate(myVar = case_when(
    mpg > 20 ~ myFun(6),
    TRUE ~ 2
  ))

But it returns an error:

Error in ifelse(cyl == x, 1, NA_real_) : object 'cyl' not found 

How should I rewrite the function to make it work?