diff --git a/src/wormhole/codes.py b/src/wormhole/codes.py
index dfa4625..708b289 100644
--- a/src/wormhole/codes.py
+++ b/src/wormhole/codes.py
@@ -94,7 +94,7 @@ def input_code_with_completion(prompt, initial_channelids, get_channel_ids,
         import readline
         c = CodeInputter(initial_channelids, get_channel_ids, code_length,
                          used_completion_f)
-        if "libedit" in readline.__doc__:
+        if readline.__doc__ and "libedit" in readline.__doc__:
             readline.parse_and_bind("bind ^I rl_complete")
         else:
             readline.parse_and_bind("tab: complete")