--- glibc-2.15-a316c1f/nscd/nscd_helper.c.orig	2012-02-11 20:25:37.804514879 -0200
+++ glibc-2.15-a316c1f/nscd/nscd_helper.c	2012-02-11 20:26:07.428588082 -0200
@@ -414,7 +414,8 @@ __nscd_get_mapping (request_type type, c
   struct mapped_database *oldval = *mappedp;
   *mappedp = result;
 
-  if (oldval != NULL && atomic_decrement_val (&oldval->counter) == 0)
+  if (oldval != NULL && oldval != NO_MAPPING
+      && atomic_decrement_val (&oldval->counter) == 0)
     __nscd_unmap (oldval);
 
   return result;