diff --git a/libguile/threads.c b/libguile/threads.c
index c1b9c3982..04897e383 100644
--- a/libguile/threads.c
+++ b/libguile/threads.c
@@ -1,5 +1,5 @@
 /* Copyright (C) 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2003, 2004,
- *   2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
+ *   2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
  *   Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
@@ -1058,7 +1058,10 @@ SCM_DEFINE (scm_call_with_new_thread, "call-with-new-thread", 1, 1, 0,
       errno = err;
       scm_syserror (NULL);
     }
-  scm_i_scm_pthread_cond_wait (&data.cond, &data.mutex);
+
+  while (scm_is_false (data.thread))
+    scm_i_scm_pthread_cond_wait (&data.cond, &data.mutex);
+
   scm_i_pthread_mutex_unlock (&data.mutex);
 
   return data.thread;
@@ -1135,7 +1138,10 @@ scm_spawn_thread (scm_t_catch_body body, void *body_data,
       errno = err;
       scm_syserror (NULL);
     }
-  scm_i_scm_pthread_cond_wait (&data.cond, &data.mutex);
+
+  while (scm_is_false (data.thread))
+    scm_i_scm_pthread_cond_wait (&data.cond, &data.mutex);
+
   scm_i_pthread_mutex_unlock (&data.mutex);
 
   assert (SCM_I_IS_THREAD (data.thread));