Ciao, I wrok into Pharo Pharo1.4 Latest update: #14445 I have a strange behavior relative to hash and = methods into one class. Sometimes when i do the code aBag occurrencesOf: anItem the system answer 0 but into the bag there's the relative anItem instance. The problem is generated when in the anItem class definitions method, i do reference to a instance variable ( consumer ) setting to a Symbol. The hash method is: hash ^item hash bitXor:( opzioniVoce hash bitXor:( referenceTime hash bitXor:( consumer hash bitXor:( newEntry hash )))) The = method is: = anItem | rslPrz | anItem ifNil:[^false]. self class = anItem class ifFalse:[ ^false]. rslPrz:= ( item = anItem item and:[ opzioniVoce = anItem opzioniVoce and:[ referenceTime = anItem referenceTime and:[ consumer = anItem consumer and:[ newEntry = anItem newEntry ]]]]). ^ rslPrz If i remove the consumer instance reference in the two methods all work fine. any ideas about it ? Thanks, Dario