diff --git a/kallithea/controllers/pullrequests.py b/kallithea/controllers/pullrequests.py
--- a/kallithea/controllers/pullrequests.py
+++ b/kallithea/controllers/pullrequests.py
@@ -541,7 +541,10 @@ class PullrequestsController(BaseRepoCon
                             hgrepo = org_scm_instance._repo
                         show = set(hgrepo.revs('::%ld & !::parents(%s) & !::%s',
                                                avail_revs, revs[0], targethead))
-                        c.update_msg = _('The following additional changes are available on %s:') % c.cs_branch_name
+                        if show:
+                            c.update_msg = _('The following additional changes are available on %s:') % c.cs_branch_name
+                        else:
+                            c.update_msg = _('No additional changesets found for iterating on this pull request.')
                     else:
                         show = set()
                         avail_revs = set() # drop revs[0]
diff --git a/kallithea/templates/pullrequests/pullrequest_show.html b/kallithea/templates/pullrequests/pullrequest_show.html
--- a/kallithea/templates/pullrequests/pullrequest_show.html
+++ b/kallithea/templates/pullrequests/pullrequest_show.html
@@ -136,7 +136,7 @@ ${self.repo_context_bar('showpullrequest
           <label>${_('Next iteration')}:</label>
             <div>
               <p>${c.update_msg}</p>
-              %if c.avail_revs:
+              %if c.avail_cs:
               <div id="updaterevs" class="clearfix">
                 <div id="updaterevs-graph">
                   <canvas id="avail_graph_canvas"></canvas>