2 files changed, 12 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 44bc26cd..2d87676a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2013-12-13  Kaz Kylheku  <kaz@kylheku.com>
 
+	* signal.c (set_sig_handler): Disable signals around this
+	function because it manipulates the mask of deferred
+	signals which can also be manipulated by an async signal.
+
+2013-12-13  Kaz Kylheku  <kaz@kylheku.com>
+
 	* signal.c (set_sig_handler): Clear the deferred flag
 	for a signal that is being set to ignored or default.
 
diff --git a/signal.c b/signal.c
index c833131b..4a089caf 100644
--- a/signal.c
+++ b/signal.c
@@ -130,6 +130,10 @@ val set_sig_handler(val signo, val lambda)
 {
   cnum sig = c_num(signo);
   val old_lambda;
+  sigset_t block, saved;
+
+  sigfillset(&block);
+  sigprocmask(SIG_BLOCK, &block, &saved);
 
   if (sig < 0 || sig >= MAX_SIG)
     uw_throwf(error_s, lit("set-sig-handler: signal ~s out of range\n"), sig, nao);
@@ -159,6 +163,8 @@ val set_sig_handler(val signo, val lambda)
     sig_lambda[sig] = lambda;
   }
 
+  sigprocmask(SIG_SETMASK, &saved, 0);
+
   return old_lambda;
 }