diff --git a/game/commander/packagebuilder.py b/game/commander/packagebuilder.py
index ad20eb72..80bc727e 100644
--- a/game/commander/packagebuilder.py
+++ b/game/commander/packagebuilder.py
@@ -104,4 +104,6 @@ class PackageBuilder:
         """Returns any planned flights to the inventory."""
         flights = list(self.package.flights)
         for flight in flights:
+            if flight.callsign is not None:
+                self.callsign_generator.release_callsign(flight.callsign)
             self.package.remove_flight(flight)