diff --git a/src/wormhole/wormhole.py b/src/wormhole/wormhole.py
index a7a8606..d1962b4 100644
--- a/src/wormhole/wormhole.py
+++ b/src/wormhole/wormhole.py
@@ -89,7 +89,7 @@ class _DelegatedWormhole(object):
     def close(self):
         self._boss.close()
 
-    def debug_set_trace(self, client_name, which="B N M S O K R RC L C T",
+    def debug_set_trace(self, client_name, which="B N M S O K SK R RC L C T",
                         file=sys.stderr):
         self._boss._set_trace(client_name, which, file)
 
@@ -212,7 +212,7 @@ class _DeferredWormhole(object):
         self._boss.close() # only need to close if it wasn't already
         return d
 
-    def debug_set_trace(self, client_name, which="B N M S O K R RC L C T",
+    def debug_set_trace(self, client_name, which="B N M S O K SK R RC L C T",
                         file=sys.stderr):
         self._boss._set_trace(client_name, which, file)