I The enemy attack bug in the NES version of Final Fantasy makes status ailments inflicted by standard enemy attacks exempt from items intended to make characters immune to them.

For example, a Knight with an Aegis Shield should be immune to Stone, but a Cockatrice can still turn him to stone as a side-effect of its regular attack.

This bug makes Mindflayers especially dangerous, since their attacks have an instant death side-effect that the Protect Ring cannot prevent.

This bug was corrected in all subsequent ports and remakes.