  I argue that the rules of unitary quantum mechanics imply that observers who
will themselves be subject to measurements in a linear combination of
macroscopic states (``cat" measurements) cannot make reliable predictions on
the results of experiments performed after such measurements. This lifts the
inconsistency in the interpretation of quantum mechanics recently identified by
Frauchiger and Renner. The Born rules for calculating the probability of
outcomes and for communicating with other observers do not generally apply for
cat-measured observers, nor can they generally be amended to incorporate
upcoming cat measurements. Quantum mechanical rules completed with these
conditions become fully consistent.
