diff --git a/frc971/control_loops/python/control_loop.py b/frc971/control_loops/python/control_loop.py
index 7301390..65cb676 100644
--- a/frc971/control_loops/python/control_loop.py
+++ b/frc971/control_loops/python/control_loop.py
@@ -420,6 +420,8 @@
       ans.append(self._DumpMatrix('P_steady_state', self.P_steady_state))
       ans.append('  return %s(Q_continuous, R_continuous, P_steady_state);\n' % (
           observer_coefficient_type,))
+    else:
+      glog.fatal('Unsupported observer type %s', observer_coefficient_type)
 
     ans.append('}\n')
     return ''.join(ans)