diff --git a/Lib/uuid.py b/Lib/uuid.py
index df51464..5684ad7 100644
--- a/Lib/uuid.py
+++ b/Lib/uuid.py
@@ -373,10 +373,13 @@
             pipe = os.popen(os.path.join(dir, 'ipconfig') + ' /all')
         except IOError:
             continue
-        for line in pipe:
-            value = line.split(':')[-1].strip().lower()
-            if re.match('([0-9a-f][0-9a-f]-){5}[0-9a-f][0-9a-f]', value):
-                return int(value.replace('-', ''), 16)
+        else:
+            for line in pipe:
+                value = line.split(':')[-1].strip().lower()
+                if re.match('([0-9a-f][0-9a-f]-){5}[0-9a-f][0-9a-f]', value):
+                    return int(value.replace('-', ''), 16)
+        finally:
+            pipe.close()
 
 def _netbios_getnode():
     """Get the hardware address on Windows using NetBIOS calls.