Fix a segmentation fault.

diff --git a/thread.c b/thread.c
index bd45392f6d51e344a49c468be8ac87edc8f10433..1f0ad33e366d52e17d41757475bef16887f5bae5 100644 (file)
--- a/thread.c
+++ b/thread.c
@@ -1272,7 +1272,7 @@ int mutt_messages_in_thread (CONTEXT *ctx, HEADER *hdr, int flag)
   THREAD *threads[2];
   int i, rc;
 
-  if ((Sort & SORT_MASK) != SORT_THREADS)
+  if ((Sort & SORT_MASK) != SORT_THREADS || !hdr->thread)
     return (1);
 
   threads[0] = hdr->thread;