diff -ur mutt-1.6.0-orig/imap/imap.c mutt-1.6.0/imap/imap.c
--- mutt-1.6.0-orig/imap/imap.c	2016-04-02 19:12:22.000000000 +0100
+++ mutt-1.6.0/imap/imap.c	2016-04-18 14:08:01.016584276 +0100
@@ -1125,7 +1125,7 @@
   if (!idata->ctx)
     return -1;
 
-  if (!mutt_bit_isset (idata->ctx->rights, right))
+  if (!idata->ctx || !mutt_bit_isset (idata->ctx->rights, right))
     return 0;
 
   if (right == M_ACL_WRITE && !imap_has_flag (idata->flags, name))