diff -r 7f1e1ba3d16b -r 75b414b298f5 hgext3rd/topic/discovery.py
--- a/hgext3rd/topic/discovery.py	Thu Apr 18 13:02:52 2019 +0200
+++ b/hgext3rd/topic/discovery.py	Thu Apr 18 13:03:01 2019 +0200
@@ -198,7 +198,7 @@
 
 def wireprotocaps(orig, repo, proto):
     caps = orig(repo, proto)
-    if repo.peer().capable('topics'):
+    if common.hastopicext(repo) and repo.peer().capable('topics'):
         caps.append('topics')
     return caps