diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 71717883e..506a63bcd 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2014-02-20  Corinna Vinschen  <corinna@vinschen.de>
+
+	* grp.cc (get_groups): Don't add gid to list if it's ILLEGAL_GID.
+	(getgrouplist): Return number of groups, just like glibc.
+
 2014-02-19  Corinna Vinschen  <corinna@vinschen.de>
 
 	* passwd.cc (pg_ent::setent): Initialize cygheap domain info.
diff --git a/winsup/cygwin/grp.cc b/winsup/cygwin/grp.cc
index 18e091642..665cb173d 100644
--- a/winsup/cygwin/grp.cc
+++ b/winsup/cygwin/grp.cc
@@ -570,7 +570,7 @@ get_groups (const char *user, gid_t gid, cygsidlist &gsids)
   cygsid usersid, grpsid;
   if (usersid.getfrompw (pw))
     get_server_groups (gsids, usersid, pw);
-  if (grpsid.getfromgr (grp))
+  if (gid != ILLEGAL_GID && grpsid.getfromgr (grp))
     gsids += grpsid;
   cygheap->user.reimpersonate ();
 }
@@ -626,7 +626,7 @@ getgrouplist (const char *user, gid_t gid, gid_t *groups, int *ngroups)
       }
   if (cnt > *ngroups)
     ret = -1;
-  *ngroups = cnt;
+  ret = *ngroups = cnt;
 
   syscall_printf ( "%d = getgrouplist(%s, %u, %p, %d)",
 		  ret, user, gid, groups, *ngroups);