diff --git a/ROSCO_testing/ROSCO_testing.py b/ROSCO_testing/ROSCO_testing.py
index f4daf300f..c8ba3ab43 100644
--- a/ROSCO_testing/ROSCO_testing.py
+++ b/ROSCO_testing/ROSCO_testing.py
@@ -389,7 +389,7 @@ def ROSCO_Controller_Comp(self, controller_paths, testtype='light'):
             elif testtype.lower() == 'heavy':
                 self.ROSCO_Test_heavy()
             else:
-                ValueError('{} is an invalid testtype for controller comparison'.format(testtype))
+                raise ValueError('{} is an invalid testtype for controller comparison'.format(testtype))
 
         # reset self
         self.runDir = run_dir_init
@@ -425,7 +425,7 @@ def ROSCO_DISCON_Comp(self, DISCON_filenames, testtype='light'):
             elif testtype.lower() == 'heavy':
                 self.ROSCO_Test_heavy(more_case_inputs=more_case_inputs)
             else:
-                ValueError('{} is an invalid testtype for DISCON comparison'.format(testtype))
+                raise ValueError('{} is an invalid testtype for DISCON comparison'.format(testtype))
 
         # reset self
         self.runDir = run_dir_init