diff --git a/examples/conjunctive_graphs.py b/examples/conjunctive_graphs.py
index f714d9ff..a66a3aa8 100644
--- a/examples/conjunctive_graphs.py
+++ b/examples/conjunctive_graphs.py
@@ -33,7 +33,7 @@ if __name__ == "__main__":
     gmary.add((mary, ns["hasName"], Literal("Mary")))
     gmary.add((mary, ns["loves"], john))
 
-    # add a graph for Mary's facts to the Conjunctive Graph
+    # add a graph for John's facts to the Conjunctive Graph
     gjohn = Graph(store=store, identifier=cjohn)
     # John's graph contains his cute name
     gjohn.add((john, ns["hasCuteName"], Literal("Johnny Boy")))
diff --git a/rdflib/namespace.py b/rdflib/namespace.py
index 84cbe508..27f6d9ea 100644
--- a/rdflib/namespace.py
+++ b/rdflib/namespace.py
@@ -804,7 +804,7 @@ class NamespaceManager(object):
 NAME_START_CATEGORIES = ["Ll", "Lu", "Lo", "Lt", "Nl"]
 SPLIT_START_CATEGORIES = NAME_START_CATEGORIES + ["Nd"]
 NAME_CATEGORIES = NAME_START_CATEGORIES + ["Mc", "Me", "Mn", "Lm", "Nd"]
-ALLOWED_NAME_CHARS = [u"\u00B7", u"\u0387", u"-", u".", u"_", u":"]
+ALLOWED_NAME_CHARS = [u"\u00B7", u"\u0387", u"-", u".", u"_", u":", u"%"]
 
 
 # http://www.w3.org/TR/REC-xml-names/#NT-NCName

diff --git a/test/test_issue801.py b/test/test_issue801.py
new file mode 100644
index 00000000..ae27f346
--- /dev/null
+++ b/test/test_issue801.py
@@ -0,0 +1,19 @@
+"""
+Issue 801 - Problem with prefixes created for URIs containing %20
+"""
+from rdflib import Namespace, Graph, BNode, Literal
+import unittest
+
+class TestIssue801(unittest.TestCase):
+
+    def test_issue_801(self):
+        g = Graph()
+        example = Namespace('http://example.org/')
+        g.bind('', example)
+        node = BNode()
+        g.add((node, example['first%20name'], Literal('John')))
+        self.assertEqual(g.serialize(format="turtle").decode().split("\n")[-3],
+                '[] :first%20name "John" .')
+
+if __name__ == "__main__":
+    unittest.main()

Minor typo(?) in example
I think the comment on line 36 is wrong and should read
```
# add a graph for John's facts to the Conjunctive Graph 
```
https://github.com/RDFLib/rdflib/blob/e4fe0fdbd4de7e1183418f302315b51a14602e03/examples/conjunctive_graphs.py#L36-L37

No big deal, but it may be confusing to learners.
test/test_issue801.py::TestIssue801::test_issue_801