Index: Lib/uu.py
===================================================================
--- Lib/uu.py	(revision 85974)
+++ Lib/uu.py	(working copy)
@@ -44,6 +44,7 @@
     #
     # If in_file is a pathname open it and change defaults
     #
+    opened_files = []
     if in_file == '-':
         in_file = sys.stdin.buffer
     elif isinstance(in_file, str):
@@ -55,6 +56,7 @@
             except AttributeError:
                 pass
         in_file = open(in_file, 'rb')
+        opened_files.append(in_file)
     #
     # Open out_file if it is a pathname
     #
@@ -62,6 +64,7 @@
         out_file = sys.stdout.buffer
     elif isinstance(out_file, str):
         out_file = open(out_file, 'wb')
+        opened_files.append(out_file)
     #
     # Set defaults for name and mode
     #
@@ -78,6 +81,8 @@
         out_file.write(binascii.b2a_uu(data))
         data = in_file.read(45)
     out_file.write(b' \nend\n')
+    for f in opened_files:
+        f.close()
 
 
 def decode(in_file, out_file=None, mode=None, quiet=False):