diff --git a/Lib/test/test_genericpath.py b/Lib/test/test_genericpath.py
index fc0c33d430f..af501cf0c76 100644
--- a/Lib/test/test_genericpath.py
+++ b/Lib/test/test_genericpath.py
@@ -47,6 +47,18 @@ class GenericTest(unittest.TestCase):
             commonprefix(["/home/swen/spam", "/home/swen/spam"]),
             "/home/swen/spam"
         )
+        self.assertEqual(
+            commonprefix(["home:swenson:spam", "home:swen:spam"]),
+            "home:swen"
+        )
+        self.assertEqual(
+            commonprefix([":home:swen:spam", ":home:swen:eggs"]),
+            ":home:swen:"
+        )
+        self.assertEqual(
+            commonprefix([":home:swen:spam", ":home:swen:spam"]),
+            ":home:swen:spam"
+        )
 
         testlist = ['', 'abc', 'Xbcd', 'Xb', 'XY', 'abcd',
                     'aXc', 'abd', 'ab', 'aX', 'abcX']
diff --git a/Lib/test/test_macpath.py b/Lib/test/test_macpath.py
index b29ed4c02c7..2c86c532c7e 100644
--- a/Lib/test/test_macpath.py
+++ b/Lib/test/test_macpath.py
@@ -18,16 +18,6 @@ class MacPathTestCase(unittest.TestCase):
         self.assertFalse(isabs(":foo:bar"))
         self.assertFalse(isabs(":foo:bar:"))
 
-
-    def test_commonprefix(self):
-        commonprefix = macpath.commonprefix
-        self.assertEqual(commonprefix(["home:swenson:spam", "home:swen:spam"]),
-                         "home:swen")
-        self.assertEqual(commonprefix([":home:swen:spam", ":home:swen:eggs"]),
-                         ":home:swen:")
-        self.assertEqual(commonprefix([":home:swen:spam", ":home:swen:spam"]),
-                         ":home:swen:spam")
-
     def test_split(self):
         split = macpath.split
         self.assertEqual(split("foo:bar"),