--- a/emu/timer_xsb.c
+++ b/emu/timer_xsb.c
@@ -264,7 +264,7 @@ int make_timed_call(CTXTdeclc xsbTimeout *pptr,  void (*fptr)(xsbTimeout *))
   pptr->timeout_info.th=th;
   // below, fptr is pointer to start routine, pptr is pointer to arg-array.
   // TIMED_THREAD_CREATE_ARG is a cell of timeout_info.
-  if (pthread_create(TIMED_THREAD_CREATE_ARG, NULL, fptr, pptr)) {
+  if (pthread_create(TIMED_THREAD_CREATE_ARG, NULL, (void *)fptr, pptr)) {
     xsb_error("SOCKET_REQUEST: Can't create concurrent timer thread\n");
     return TIMER_SETUP_ERR;
   }