diff --git a/src/calibre/customize/__init__.py b/src/calibre/customize/__init__.py
index 3b6f1cd760..456c9fba93 100644
--- a/src/calibre/customize/__init__.py
+++ b/src/calibre/customize/__init__.py
@@ -119,11 +119,34 @@ class Plugin(object):
 
     def __enter__(self, *args):
         if self.plugin_path is not None:
-            sys.path.insert(0, self.plugin_path)
+            from calibre.utils.zipfile import ZipFile
+            zf = ZipFile(self.plugin_path)
+            extensions = set([x.rpartition('.')[-1].lower() for x in
+                zf.namelist()])
+            zip_safe = True
+            for ext in ('pyd', 'so', 'dll', 'dylib'):
+                if ext in extensions:
+                    zip_safe = False
+            if zip_safe:
+                sys.path.insert(0, self.plugin_path)
+                self._sys_insertion_path = self.plugin_path
+            else:
+                from calibre.ptempfile import TemporaryDirectory
+                self._sys_insertion_tdir = TemporaryDirectory('plugin_unzip')
+                self._sys_insertion_path = self._sys_insertion_tdir.__enter__(*args)
+                zf.extractall(self._sys_insertion_path)
+                sys.path.insert(0, self._sys_insertion_path)
+            zf.close()
+
 
     def __exit__(self, *args):
-        if self.plugin_path in sys.path:
-            sys.path.remove(self.plugin_path)
+        ip, it = getattr(self, '_sys_insertion_path', None), getattr(self,
+                '_sys_insertion_tdir', None)
+        if ip in sys.path:
+            sys.path.remove(ip)
+        if hasattr(it, '__exit__'):
+            it.__exit__(*args)
+
 
 
 class FileTypePlugin(Plugin):
@@ -183,6 +206,7 @@ class MetadataReaderPlugin(Plugin):
     type = _('Metadata reader')
 
     def __init__(self, *args, **kwargs):
+        print 11111, args, kwargs
         Plugin.__init__(self, *args, **kwargs)
         self.quick = False
 
diff --git a/src/calibre/customize/ui.py b/src/calibre/customize/ui.py
index 0f072d1f70..68c26386c9 100644
--- a/src/calibre/customize/ui.py
+++ b/src/calibre/customize/ui.py
@@ -401,7 +401,7 @@ def initialize_plugins():
                 plugin = load_plugin(zfp) if not isinstance(zfp, type) else zfp
             except PluginNotFound:
                 continue
-            plugin = initialize_plugin(plugin, zfp if not isinstance(zfp, type) else zfp)
+            plugin = initialize_plugin(plugin, None if isinstance(zfp, type) else zfp)
             _initialized_plugins.append(plugin)
         except:
             print 'Failed to initialize plugin...'