diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1643,8 +1643,8 @@ class localrepository(object):
         linear_path = (pa == p1 or pa == p2)
 
         if allow and linear_path:
-            raise util.Abort(_("there is nothing to merge, "
-                               "just use 'hg update'"))
+            raise util.Abort(_("there is nothing to merge, just use "
+                               "'hg update' or look at 'hg heads'"))
         if allow and not forcemerge:
             if modified or added or removed:
                 raise util.Abort(_("outstanding uncommitted changes"))