Hi Harald, thank you for the investigation and useful tips. I had to figure what went wrong here, but I now figured, that the array needs repacking when a negative stride is used (or at least a call to that routine, which then fixes "stuff"). I have added it, freeing the memory allocated potentially by pack, and also updated the testcase to include the negative stride. Regtests fine on x86_64-pc-linux-gnu/Fedora 39. Ok for mainline? Regards, Andre On Sun, 16 Jun 2024 23:27:46 +0200 Harald Anlauf wrote: << snipped for brevity >>> -- Andre Vehreschild * Email: vehre ad gmx dot de