CSS3 Animation On enter scaling timing function

I'm trying to get the animation to scale up and down in a bouncy way using the animation timing function.

@keyframes iconEnter
  0%
    transform scale(0)
  100%
    transform scale(1)
    animation-timing-function cubic-bezier(.1,.85,.1,1)

.icon
  animation iconEnter 5s

This just scales linearly without the timing function being applied. What am I doing wrong?

Thanks.