diff --git a/spice_test_suite/run_spice_tests_new.py b/spice_test_suite/run_spice_tests_new.py
index 79910a2..21366a3 100755
--- a/spice_test_suite/run_spice_tests_new.py
+++ b/spice_test_suite/run_spice_tests_new.py
@@ -484,6 +484,9 @@
     elif "_res" in devicename:
         devicetype = 'resistor'
 
+    else:
+        raise SystemError('Unknown device:'+devicename)
+
     # Check list of devices for additional sub-types
     if devicetype == 'nfet':
         if devicename in five_pin_fets: