diff --git a/.aspell.en.pws b/.aspell.en.pws
index d44ec5b..143c035 100644
--- a/.aspell.en.pws
+++ b/.aspell.en.pws
@@ -300,3 +300,4 @@ remotehtlcsig
 localhtlcsig
 basepoints
 Bitcoins
+deobfuscate
diff --git a/04-onion-routing.md b/04-onion-routing.md
index fa67ad4..685f8e6 100644
--- a/04-onion-routing.md
+++ b/04-onion-routing.md
@@ -630,7 +630,7 @@ The origin node:
   - once the return message has been decrypted:
     - SHOULD store a copy of the message.
     - SHOULD continue decrypting, until the loop has been repeated 20 times.
-    - SHOULD use constant `ammag` and `um` keys to de-obfuscate the route length.
+    - SHOULD use constant `ammag` and `um` keys to deobfuscate [FIXME: is this correct? was 'obfuscate'] the route length.
 
 The association between the forward and return packets is handled outside of
 this onion routing protocol, e.g. via association with an HTLC in a payment