diff --git a/isbnlib/test/test_core.py b/isbnlib/test/test_core.py
index 5b7858e3..df4be954 100644
--- a/isbnlib/test/test_core.py
+++ b/isbnlib/test/test_core.py
@@ -118,6 +118,7 @@ def test_canonical():
     assert_equals(canonical('ISBN9780826497529'), '9780826497529')
     assert_equals(canonical('isbn9780826497529'), '9780826497529')
     assert_equals(canonical('isbn 0826497527'), '0826497527')
+    assert_equals(get_canonical_isbn('954430603x'), '954430603X')
 
 
 def test_EAN13():