Index: libcfa/src/bits/signal.hfa
===================================================================
--- libcfa/src/bits/signal.hfa	(revision 1712f542a5ea4d2772859a9d4ca18e5f865db7cb)
+++ libcfa/src/bits/signal.hfa	(revision 596fc4ad0bfcf63b10c655b945c772325da80ac9)
@@ -37,4 +37,7 @@
 
 	act.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
+	sigemptyset( &act.sa_mask );
+	sigaddset( &act.sa_mask, SIGALRM );		// disabled during signal handler
+	sigaddset( &act.sa_mask, SIGUSR1 );
 	act.sa_flags = flags;