diff --git a/tests/scripts/test_psa_constant_names.py b/tests/scripts/test_psa_constant_names.py
index a40a82959f..a43a3e888f 100755
--- a/tests/scripts/test_psa_constant_names.py
+++ b/tests/scripts/test_psa_constant_names.py
@@ -100,6 +100,17 @@ class Inputs:
             'tag_length': ['1', '63'],
         }
 
+    def get_names(self, type_word):
+        """Return the set of known names of values of the given type."""
+        return {
+            'status': self.statuses,
+            'algorithm': self.algorithms,
+            'ecc_curve': self.ecc_curves,
+            'dh_group': self.dh_groups,
+            'key_type': self.key_types,
+            'key_usage': self.key_usage_flags,
+        }[type_word]
+
     def gather_arguments(self):
         """Populate the list of values for macro arguments.
 
@@ -313,7 +324,7 @@ def normalize(expr):
     """
     return re.sub(NORMALIZE_STRIP_RE, '', expr)
 
-def do_test(options, inputs, type_word, names):
+def do_test(options, inputs, type_word):
     """Test psa_constant_names for the specified type.
 
     Run program on names.
@@ -324,6 +335,7 @@ def do_test(options, inputs, type_word, names):
     that have been tested and ``errors`` is the list of errors that were
     encountered.
     """
+    names = inputs.get_names(type_word)
     expressions = sorted(inputs.generate_expressions(names))
     values = run_c(options, type_word, expressions)
     output = subprocess.check_output([options.program, type_word] + values)
@@ -348,13 +360,9 @@ def run_tests(options, inputs):
     """
     count = 0
     errors = []
-    for type_word, names in [('status', inputs.statuses),
-                             ('algorithm', inputs.algorithms),
-                             ('ecc_curve', inputs.ecc_curves),
-                             ('dh_group', inputs.dh_groups),
-                             ('key_type', inputs.key_types),
-                             ('key_usage', inputs.key_usage_flags)]:
-        c, e = do_test(options, inputs, type_word, names)
+    for type_word in ['status', 'algorithm', 'ecc_curve', 'dh_group',
+                      'key_type', 'key_usage']:
+        c, e = do_test(options, inputs, type_word)
         count += c
         errors += e
     return count, errors