diff --git a/nullptr/missions/base.py b/nullptr/missions/base.py
index c6344c0..192a33e 100644
--- a/nullptr/missions/base.py
+++ b/nullptr/missions/base.py
@@ -224,7 +224,7 @@ class BaseMission(Mission):
     self.api.dock(self.ship)
  
   def step_refuel(self):
-    if self.ship.fuel_current < 100:
+    if self.ship.fuel_current / self.ship.fuel_capacity < 0.5:
       try:
         self.api.refuel(self.ship)
       except Exception as e: