Hi, I tried mudflap on the following simple program, that has no errors as far as I can see this: #include <malloc.h> #include <stdio.h> void print(int * a) { printf("%d\n", *a); } int main (void) { int * a = malloc(sizeof(int)); *a = 2; print(a); free(a); return 0; } Here is the result of mudflap after compiling with: gcc mud.c -pthread -fmudflapth -lmudflapth export MUDFLAP_OPTIONS="-print-leaks" ./a.out 2 ******* mudflap warning: unaccessed registered object: mudflap dead object 0x804cce0: name=`malloc region' bounds=[0x804cc98,0x804cc9b] size=4 area=heap check=0r/0w liveness=0 alloc time=1155905084.555647 pc=0xb7e124b0 thread=3083499184 /home/devel/software/gcc/lib/libmudflapth.so.0(__mf_register+0x50) [0xb7e124b0] /home/devel/software/gcc/lib/libmudflapth.so.0(__real_malloc+0xf2) [0xb7e13b22] ./a.out(main+0x1d) [0x804865e] /home/devel/software/gcc/lib/libmudflapth.so.0(__wrap_main+0x49) [0xb7e12579] dealloc time=1155905084.556104 pc=0xb7e123d9 thread=3083499184 /home/devel/software/gcc/lib/libmudflapth.so.0(__mf_unregister+0x49) [0xb7e123d9] /home/devel/software/gcc/lib/libmudflapth.so.0(__real_free+0xad) [0xb7e132ed] ./a.out(main+0x3f) [0x8048680] /home/devel/software/gcc/lib/libmudflapth.so.0(__wrap_main+0x49) [0xb7e12579] number of leaked objects: 0 In our real multithreaded programm we get tons of such messages. What is the error shown here? And how to prevent it? When I compile the test programm without threads it works fine, but this is no option for the real programm. The gcc version: gcc (GCC) 4.1.1 Greetings Christoph Bartoschek