diff --git a/Tools/autotest/arducopter.py b/Tools/autotest/arducopter.py
index fe808916d4..372bd1b7da 100644
--- a/Tools/autotest/arducopter.py
+++ b/Tools/autotest/arducopter.py
@@ -9462,9 +9462,6 @@ class AutoTestCopter(vehicle_test_suite.TestSuite):
                 self.progress("Actually, no I'm not - it is an external simulation")
                 continue
             model = frame_bits.get("model", frame)
-            # the model string for Callisto has crap in it.... we
-            # should really have another entry in the vehicleinfo data
-            # to carry the path to the JSON.
             defaults = self.model_defaults_filepath(frame)
             if not isinstance(defaults, list):
                 defaults = [defaults]
diff --git a/Tools/autotest/arduplane.py b/Tools/autotest/arduplane.py
index 0fe87ca3d8..e04763c3fc 100644
--- a/Tools/autotest/arduplane.py
+++ b/Tools/autotest/arduplane.py
@@ -4219,11 +4219,7 @@ class AutoTestPlane(vehicle_test_suite.TestSuite):
                 self.progress("Actually, no I'm not - it is an external simulation")
                 continue
             model = frame_bits.get("model", frame)
-            # the model string for Callisto has crap in it.... we
-            # should really have another entry in the vehicleinfo data
-            # to carry the path to the JSON.
-            actual_model = model.split(":")[0]
-            defaults = self.model_defaults_filepath(actual_model)
+            defaults = self.model_defaults_filepath(frame)
             if not isinstance(defaults, list):
                 defaults = [defaults]
             self.customise_SITL_commandline(