diff --git a/sphinx/apidoc.py b/sphinx/apidoc.py
index 4a64dd33b..346956d31 100644
--- a/sphinx/apidoc.py
+++ b/sphinx/apidoc.py
@@ -21,6 +21,8 @@ import sys
 import optparse
 from os import path
 
+from sphinx.util.osutil import walk
+
 # automodule options
 if 'SPHINX_APIDOC_OPTIONS' in os.environ:
     OPTIONS = os.environ['SPHINX_APIDOC_OPTIONS'].split(',')
@@ -185,7 +187,7 @@ def recurse_tree(rootpath, excludes, opts):
     toplevels = []
     followlinks = getattr(opts, 'followlinks', False)
     includeprivate = getattr(opts, 'includeprivate', False)
-    for root, subs, files in os.walk(rootpath, followlinks=followlinks):
+    for root, subs, files in walk(rootpath, followlinks=followlinks):
         # document only Python module files (that aren't excluded)
         py_files = sorted(f for f in files
                           if path.splitext(f)[1] in PY_SUFFIXES and
diff --git a/sphinx/writers/html.py b/sphinx/writers/html.py
index 765ee9055..13dd5d424 100644
--- a/sphinx/writers/html.py
+++ b/sphinx/writers/html.py
@@ -405,7 +405,10 @@ class HTMLTranslator(BaseTranslator):
                         node['width'] = str(im.size[0])
                     if 'height' not in node:
                         node['height'] = str(im.size[1])
-                    del im
+                    try:
+                        im.fp.close()
+                    except Exception:
+                        pass
         BaseTranslator.visit_image(self, node)
 
     def visit_toctree(self, node):