diff --git a/src/calibre/customize/ui.py b/src/calibre/customize/ui.py
index 4b2aa18a2b..59e8968c9d 100644
--- a/src/calibre/customize/ui.py
+++ b/src/calibre/customize/ui.py
@@ -3,6 +3,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import os, shutil, traceback, functools, sys, re
+from contextlib import closing
 
 from calibre.customize import Plugin, FileTypePlugin, MetadataReaderPlugin, \
                               MetadataWriterPlugin
@@ -51,25 +52,25 @@ def load_plugin(path_to_zip_file):
     #print 'Loading plugin from', path_to_zip_file
     if not os.access(path_to_zip_file, os.R_OK):
         raise PluginNotFound
-    zf = ZipFile(path_to_zip_file)
-    for name in zf.namelist():
-        if name.lower().endswith('plugin.py'):
-            locals = {}
-            raw = zf.read(name)
-            match = re.search(r'coding[:=]\s*([-\w.]+)', raw[:300])
-            encoding = 'utf-8'
-            if match is not None:
-                encoding = match.group(1)
-            raw = raw.decode(encoding)
-            raw = re.sub('\r\n', '\n', raw)
-            exec raw in locals
-            for x in locals.values():
-                if isinstance(x, type) and issubclass(x, Plugin):
-                    if x.minimum_calibre_version > version or \
-                        platform not in x.supported_platforms:
-                        continue
+    with closing(ZipFile(path_to_zip_file)) as zf:
+        for name in zf.namelist():
+            if name.lower().endswith('plugin.py'):
+                locals = {}
+                raw = zf.read(name)
+                match = re.search(r'coding[:=]\s*([-\w.]+)', raw[:300])
+                encoding = 'utf-8'
+                if match is not None:
+                    encoding = match.group(1)
+                raw = raw.decode(encoding)
+                raw = re.sub('\r\n', '\n', raw)
+                exec raw in locals
+                for x in locals.values():
+                    if isinstance(x, type) and issubclass(x, Plugin):
+                        if x.minimum_calibre_version > version or \
+                            platform not in x.supported_platforms:
+                            continue
 
-                    return x
+                        return x
 
     raise InvalidPlugin(_('No valid plugin found in ')+path_to_zip_file)