I took a look at http://bugs.squeak.org/view.php?id=7321 and http://code.google.com/p/pharo/issues/detail?id=688 I started publishing PharoInbox/SLICE-DelayFixFromMantis7321-nice to integrate Andreas' changes. Now I did integrate all but DelayCleanup.1.cs This change set does cure the failing testSemaphore in Pharo, but has two problems: 1) It requires a preamble, and I don't know how they are handled in Monticello 2) It probably does not include change about LargeInteger delays included in 3.9 (Dave kindly pointed me to http://bugs.squeak.org/view.php?id=854) 3) it makes DelayTests>>#testBounds fail I think that the limit of (SmallInteger maxVal//2) is not necessary... if LargeInteger delay fix is in the image. I can try to fix 2) mixing Andreas and Tim fixes. What about 1) ?