diff --git a/python/sbs1.py b/python/sbs1.py
index 8de8927..cfdd89d 100644
--- a/python/sbs1.py
+++ b/python/sbs1.py
@@ -52,7 +52,7 @@ class output_sbs1(air_modes.parse):
     # Checking to see if we need to clean up in the event that the
     # dictionary is getting too large.
     if len(self._aircraft_id_map) > 1e4:
-      minimum = min(self._aircraft_id_map.values()) + (len(self_aircraft_id_map) - 1e4)
+      minimum = min(self._aircraft_id_map.values()) + (len(self._aircraft_id_map) - 1e4)
       for icao, _id in self._aircraft_id_map:
         if _id < minimum:
             del self._aircraft_id_map[icao]