diff --git a/Doc/library/base64.rst b/Doc/library/base64.rst
index 4876117f6403b2..08e923c0a5244f 100644
--- a/Doc/library/base64.rst
+++ b/Doc/library/base64.rst
@@ -246,8 +246,7 @@ Refer to the documentation of the individual functions for more information.
    *adobe* controls whether the input sequence is in Adobe Ascii85 format
    (i.e. is framed with <~ and ~>).
 
-   *ignorechars* should be a :term:`bytes-like object` or ASCII string
-   containing characters to ignore
+   *ignorechars* should be a byte string containing characters to ignore
    from the input. This should only contain whitespace characters, and by
    default contains all whitespace characters in ASCII.
 
diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
index 120c5824a42a40..24f8836f1b2178 100644
--- a/Lib/test/test_base64.py
+++ b/Lib/test/test_base64.py
@@ -948,6 +948,19 @@ def test_a85decode_errors(self):
         self.assertRaises(ValueError, base64.a85decode, b'aaaay',
                           foldspaces=True)
 
+        self.assertEqual(base64.a85decode(b"a b\nc", ignorechars=b" \n"),
+                         b'\xc9\x89')
+        with self.assertRaises(ValueError):
+            base64.a85decode(b"a b\nc", ignorechars=b"")
+        with self.assertRaises(ValueError):
+            base64.a85decode(b"a b\nc", ignorechars=b" ")
+        with self.assertRaises(ValueError):
+            base64.a85decode(b"a b\nc", ignorechars=b"\n")
+        with self.assertRaises(TypeError):
+            base64.a85decode(b"a b\nc", ignorechars=" \n")
+        with self.assertRaises(TypeError):
+            base64.a85decode(b"a b\nc", ignorechars=None)
+
     def test_b85decode_errors(self):
         illegal = list(range(33)) + \
                   list(b'"\',./:[\\]') + \