Hi, I was executing this code '(2009/2000) ** (3958333/100000)' with the Pharo6.1 distribution and the vm crashed with she stack attached below. Tried it on both mac and windows 10. Seems that #raisedTo: has a special case for fractions that ends up calling #nthRoot: like '2009 nthRoot: 100000' leading to the crash. Cheers, Andrei 0xaddeac M LargePositiveInteger(Integer)>quo: 0x314093e8: a(n) LargePositiveInteger 0xaddec8 M LargePositiveInteger(LargeInteger)>quo: 0x314093e8: a(n) LargePositiveInteger 0xaddee8 M LargePositiveInteger(Integer)>// 0x314093e8: a(n) LargePositiveInteger 0xaddf04 M LargePositiveInteger(LargeInteger)>// 0x314093e8: a(n) LargePositiveInteger 0xaddf34 I LargePositiveInteger(Integer)>nthRootTruncated: 0x30cc8350: a(n) LargePositiveInteger 0xaddf5c I LargePositiveInteger(Integer)>nthRootRounded: 0x30cc8350: a(n) LargePositiveInteger 0xaddf88 I SmallInteger(Integer)>nthRoot: 0xfb3=2009 0xaddfb4 I Fraction>nthRoot: 0x4f9a940: a(n) Fraction 0xaddfd8 I Fraction(Number)>raisedTo: 0x4f9a940: a(n) Fraction 0xaddffc I Fraction(Number)>** 0x4f9a940: a(n) Fraction 0xade018 M UndefinedObject>DoIt 0x5fe5d00: a(n) UndefinedObject 0xade048 I OpalCompiler>evaluate 0x4f9a998: a(n) OpalCompiler 0xade074 I RubSmalltalkEditor>evaluate:andDo: 0x305e5878: a(n) RubSmalltalkEditor 0xade09c I RubSmalltalkEditor>highlightEvaluateAndDo: 0x305e5878: a(n) RubSmalltalkEditor 0xade0b8 M GLMMorphicPharoScriptRenderer(GLMMorphicPharoCodeRenderer)>popupPrint 0x3062fdc8: a(n) GLMMorphicPharoScri enderer 0xade0d8 I MorphicAlarm(MessageSend)>value 0x4f9ab20: a(n) MorphicAlarm 0xade0f4 M MorphicAlarm>value: 0x4f9ab20: a(n) MorphicAlarm 0xade114 M WorldState>triggerAlarmsBefore: 0x71bb5e0: a(n) WorldState 0xade140 M WorldState>runLocalStepMethodsIn: 0x71bb5e0: a(n) WorldState 0xade164 M WorldState>runStepMethodsIn: 0x71bb5e0: a(n) WorldState 0xade180 M WorldMorph>runStepMethods 0x6ab7778: a(n) WorldMorph 0xade198 M WorldState>doOneCycleNowFor: 0x71bb5e0: a(n) WorldState 0xade1b4 M WorldState>doOneCycleFor: 0x71bb5e0: a(n) WorldState 0xade1d0 M WorldMorph>doOneCycle 0x6ab7778: a(n) WorldMorph 0xade1e8 M WorldMorph class>doOneCycle 0x6a9f960: a(n) WorldMorph class 0xade200 M [] in MorphicUIManager>spawnNewProcess 0x2cc88718: a(n) MorphicUIManager 0xade220 I [] in BlockClosure>newProcess 0x2f178150: a(n) BlockClosure