Hello! I have a very easy reproducible memory leak here when using malloc/free in two threads. Attaching a simple test. thread() here is calling pthread_create(): https://github.com/yeryomin/liba/blob/master/liba.c#L181 Do I misunderstand something or is it a bug? This can be avoided by wrapping malloc into locks but not sure if that's the fix you want... Regards, Roman