diff --git a/nullptr/missions/base.py b/nullptr/missions/base.py
index 192a33e..e509dfd 100644
--- a/nullptr/missions/base.py
+++ b/nullptr/missions/base.py
@@ -224,6 +224,8 @@ class BaseMission(Mission):
     self.api.dock(self.ship)
  
   def step_refuel(self):
+    if self.ship.fuel_capacity == 0:
+      return
     if self.ship.fuel_current / self.ship.fuel_capacity < 0.5:
       try:
         self.api.refuel(self.ship)