diff --git a/asn1crypto/keys.py b/asn1crypto/keys.py
index 81ab0aa..2f79fad 100644
--- a/asn1crypto/keys.py
+++ b/asn1crypto/keys.py
@@ -1052,7 +1052,8 @@
             ValueError - when the key is not a DSA key
 
         :return:
-            A unicode string of "sha1" or "sha2"
+            A unicode string of "sha1" or "sha2" or None if no parameters are
+            present
         """
 
         if self.algorithm != 'dsa':
@@ -1064,7 +1065,11 @@
                 self.algorithm.upper()
             ))
 
-        byte_len = math.log(self['algorithm']['parameters']['q'].native, 2) / 8
+        parameters = self['algorithm']['parameters']
+        if parameters.native is None:
+            return None
+
+        byte_len = math.log(parameters['q'].native, 2) / 8
 
         return 'sha1' if byte_len <= 20 else 'sha2'
 
diff --git a/tests/fixtures/DSAParametersInheritedCACert.crt b/tests/fixtures/DSAParametersInheritedCACert.crt
new file mode 100644
index 0000000..5e2fa5b
--- /dev/null
+++ b/tests/fixtures/DSAParametersInheritedCACert.crt
Binary files differ
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 4a5586b..d3539b4 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -2813,6 +2813,74 @@
             extensions.native
         )
 
+    def test_parse_dsa_certificate_inheritance(self):
+        cert = self._load_cert('DSAParametersInheritedCACert.crt')
+
+        tbs_certificate = cert['tbs_certificate']
+        signature = tbs_certificate['signature']
+        issuer = tbs_certificate['issuer']
+        validity = tbs_certificate['validity']
+        subject = tbs_certificate['subject']
+        subject_public_key_info = tbs_certificate['subject_public_key_info']
+        subject_public_key_algorithm = subject_public_key_info['algorithm']
+
+        self.assertEqual(
+            'v3',
+            tbs_certificate['version'].native
+        )
+        self.assertEqual(
+            2,
+            tbs_certificate['serial_number'].native
+        )
+        self.assertEqual(
+            'sha1_dsa',
+            signature['algorithm'].native
+        )
+        self.assertEqual(
+            None,
+            signature['parameters'].native
+        )
+        self.assertEqual(
+            util.OrderedDict([
+                ('country_name', 'US'),
+                ('organization_name', 'Test Certificates 2011'),
+                ('common_name', 'DSA CA'),
+            ]),
+            issuer.native
+        )
+        self.assertEqual(
+            datetime(2010, 1, 1, 8, 30, tzinfo=util.timezone.utc),
+            validity['not_before'].native
+        )
+        self.assertEqual(
+            datetime(2030, 12, 31, 8, 30, tzinfo=util.timezone.utc),
+            validity['not_after'].native
+        )
+        self.assertEqual(
+            util.OrderedDict([
+                ('country_name', 'US'),
+                ('organization_name', 'Test Certificates 2011'),
+                ('common_name', 'DSA Parameters Inherited CA'),
+            ]),
+            subject.native
+        )
+        self.assertEqual(
+            'dsa',
+            subject_public_key_algorithm['algorithm'].native
+        )
+        self.assertEqual(
+            None,
+            subject_public_key_algorithm['parameters'].native
+        )
+        self.assertEqual(
+            'dsa',
+            subject_public_key_info.algorithm
+        )
+        self.assertEqual(
+            None,
+            subject_public_key_info.hash_algo
+        )
+
     def test_parse_ec_certificate(self):
         cert = self._load_cert('keys/test-ec-der.crt')