diff --git a/pokemontools/lz.py b/pokemontools/lz.py
index f9d1dfe..7ba0cd5 100644
--- a/pokemontools/lz.py
+++ b/pokemontools/lz.py
@@ -219,6 +219,9 @@ class Compressed:
 
         lookback = 0, None
 
+        self.lookbacks[method][address] = lookback
+        return lookback
+
         # Better to not carelessly optimize at the moment.
         """
         if address < 2: