diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index 9c0ce5a..ac01613 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -132,9 +132,9 @@
     def phase1(self): # Compute common names
         a = dict(izip(imap(os.path.normcase, self.left_list), self.left_list))
         b = dict(izip(imap(os.path.normcase, self.right_list), self.right_list))
-        self.common = map(a.__getitem__, ifilter(b.__contains__, a))
-        self.left_only = map(a.__getitem__, ifilterfalse(b.__contains__, a))
-        self.right_only = map(b.__getitem__, ifilterfalse(a.__contains__, b))
+        self.common = list(map(a.__getitem__, ifilter(b.__contains__, a)))
+        self.left_only = list(map(a.__getitem__, ifilterfalse(b.__contains__, a)))
+        self.right_only = list(map(b.__getitem__, ifilterfalse(a.__contains__, b)))
 
     def phase2(self): # Distinguish files, directories, funnies
         self.common_dirs = []