I criticize an account of perceptual warrant proposed by [Burge, Tyler. 2003. “Perceptual Entitlement.” Philosophy and Phenomenological Research 67 (3): 503–548]. Burge contends that a subject's beliefs are entitled only if that subject's perceptual system represents its normal environment in a reliably veridical manner. The normal environment, according to Burge, is the environment in which the contents of the subject's perceptual experiences were fixed. I present a case that shows that the contents of a subject's perceptual experiences can remain fixed (...) while features of its perceptual system relevant to its representational reliability change. This leads to problematic consequences for Burge's view. (shrink)