running Pd through valgrind  gives a number of "Invalid read" errors, as soon as you create an object and type a single letter (e.g. "f").
creating the object (by licking besides it), gives another number of "Invalid read" errors.
those errors suggest that memory outside the allocated buffer is accessed. it seems that all these errors are related to the UTF-8 code (since with utf-8 we might have to check multiple bytes).
the attached fix simply increases the allocated buffer slightly (more than what happens already), so the read can take place on safe grounds.
 like with $ valgrind --tool=memcheck --leak-check=full ./src/pd -noprefs -nrt -noaudio -stderr