diff -up cyrus-sasl-2.1.23/lib/common.c.race cyrus-sasl-2.1.23/lib/common.c
--- cyrus-sasl-2.1.23/lib/common.c.race	2010-02-22 09:57:28.000000000 +0100
+++ cyrus-sasl-2.1.23/lib/common.c	2010-02-22 09:59:30.000000000 +0100
@@ -794,7 +794,11 @@ void sasl_dispose(sasl_conn_t **pconn)
   if (result!=SASL_OK) return;
   
   /* *pconn might have become NULL by now */
-  if (! (*pconn)) return;
+  if (! (*pconn))
+  {
+	sasl_MUTEX_UNLOCK(free_mutex);
+	return;
+  }
 
   (*pconn)->destroy_conn(*pconn);
   sasl_FREE(*pconn);