diff -Naur coreutils-8.20.orig/src/timeout.c coreutils-8.20/src/timeout.c
--- coreutils-8.20.orig/src/timeout.c	2012-10-23 16:14:12.000000000 +0200
+++ coreutils-8.20/src/timeout.c	2013-01-23 18:40:09.138166579 +0100
@@ -433,6 +433,16 @@
       pid_t wait_result;
       int status;
 
+      /* assure our timeout signal SIGALRM is not blocked */
+      sigset_t unblock_set;
+      sigemptyset (&unblock_set);
+      sigaddset (&unblock_set, SIGALRM);
+      if (sigprocmask (SIG_UNBLOCK, &unblock_set, NULL) != 0)
+        {
+          error (0, 0, _("error setting signal mask"));
+          return EXIT_CANCELED;
+        }
+
       settimeout (timeout);
 
       while ((wait_result = waitpid (monitored_pid, &status, 0)) < 0