This is valgrind upsteam bug https://bugs.kde.org/show_bug.cgi?id=508145 Fix now also committed on the VALGRIND_3_25_BRANCH: https://sourceware.org/cgit/valgrind/commit/?h=VALGRIND_3_25_BRANCH The VALGRIND_3_25_BRANCH contains a couple backports that didn't make it to the last 3.25.1 release yet.