diff --git a/src/allmydata/test/test_base32.py b/src/allmydata/test/test_base32.py
index 8af0d7d71..d24fe8400 100644
--- a/src/allmydata/test/test_base32.py
+++ b/src/allmydata/test/test_base32.py
@@ -11,17 +11,21 @@ from allmydata.util import base32
 
 class Base32(unittest.TestCase):
     def test_b2a_matches_Pythons(self):
-        y = "\x12\x34\x45\x67\x89\x0a\xbc\xde\xf0"
+        y = b"\x12\x34\x45\x67\x89\x0a\xbc\xde\xf0"
         x = base64.b32encode(y)
-        while x and x[-1] == '=':
-            x = x[:-1]
+        x = x.rstrip(b"=")
         x = x.lower()
-        self.failUnlessEqual(base32.b2a(y), x)
+        result = base32.b2a(y)
+        self.failUnlessEqual(result, x)
+        self.assertIsInstance(result, bytes)
+
     def test_b2a(self):
-        self.failUnlessEqual(base32.b2a("\x12\x34"), "ci2a")
+        self.failUnlessEqual(base32.b2a(b"\x12\x34"), b"ci2a")
+
     def test_b2a_or_none(self):
         self.failUnlessEqual(base32.b2a_or_none(None), None)
-        self.failUnlessEqual(base32.b2a_or_none("\x12\x34"), "ci2a")
+        self.failUnlessEqual(base32.b2a_or_none(b"\x12\x34"), b"ci2a")
+
     def test_a2b(self):
-        self.failUnlessEqual(base32.a2b("ci2a"), "\x12\x34")
-        self.failUnlessRaises(AssertionError, base32.a2b, "b0gus")
+        self.failUnlessEqual(base32.a2b(b"ci2a"), b"\x12\x34")
+        self.failUnlessRaises(AssertionError, base32.a2b, b"b0gus")