--- a/hgext3rd/topic/__init__.py	Fri Jul 08 16:09:55 2016 +0000
+++ b/hgext3rd/topic/__init__.py	Fri Jul 08 16:59:43 2016 +0000
@@ -320,8 +320,11 @@
     def newmakeextrafn(orig, copiers):
         return orig(copiers + [savetopic])
 
-    rebase = extensions.find("rebase")
-    extensions.wrapfunction(rebase, '_makeextrafn', newmakeextrafn)
+    try:
+        rebase = extensions.find("rebase")
+        extensions.wrapfunction(rebase, '_makeextrafn', newmakeextrafn)
+    except KeyError:
+        pass
 
 ## preserve topic during import/export