Hi All, I'm trying to debug remaining limitations in Image Segment support in Spur using a case provided by Max Leske. This is a pair of Pharo 6 images, one of which saves an image segment the other which loads it. Both use OSEnvironment>>getEnv: to access environment variables. The base definition of OSEnvironment>>getEnv: is !OSEnvironment methodsFor: 'accessing' stamp: 'auto 5/3/2016 10:31'! getEnv: arg1 "This method calls the Standard C Library getenv() function. The name of the argument (arg1) should fit decompiled version." ^ self ffiCall: #( String getenv (String arg1) ) module: LibC! ! but as I'm using the VM Simulator to debug the image segment issues I need to avoid the FFI, which isn't yet simulateable. So I redefine OSEnvironment>>getEnv: as follows, and then save and exit. !OSEnvironment methodsFor: 'accessing' stamp: 'EliotMiranda 02/27/2019 17:09'! getEnv: aByteStringOrByteArray "This method calls the Standard C Library getenv() function. The name of the argument (arg1) should fit decompiled version." <primitive: 'primitiveGetenv' module: '' error: ec> ec == #'bad argument' ifTrue: [aByteStringOrByteArray isString ifFalse: [^self getEnv: aByteStringOrByteArray asString]]. self primitiveFail! ! But, and here's the weird bit, when I start up the image, the new definition has been discarded and replaced by the original. WTF?!?! Why is this happening? How can I disable this? The only way that I've found I am able to save with a new version is by doing a Save As... to a new name. This is fine, but I find the current behavior extremely unhelpful. Is it a bug? If it is intended, whats the rationale? _,,,^..^,,,_ best, Eliot