fixes #148 + test case
diff --git a/tests/primitives/test_hashes.py b/tests/primitives/test_hashes.py
index 805d992..03de891 100644
--- a/tests/primitives/test_hashes.py
+++ b/tests/primitives/test_hashes.py
@@ -28,6 +28,10 @@
         with pytest.raises(TypeError):
             m.update(six.u("\u00FC"))
 
+    def test_base_hash_hexdigest_string_type(self, api):
+        m = hashes.SHA1(api=api, data=b"")
+        assert isinstance(m.hexdigest(), str)
+
 
 class TestSHA1(object):
     test_SHA1 = generate_base_hash_test(