diff -r 74687680a283 -r a1f50d969fe8 sphinx/util/__init__.py
--- a/sphinx/util/__init__.py	Mon Oct 29 21:38:48 2012 +0900
+++ b/sphinx/util/__init__.py	Tue Oct 30 10:04:18 2012 +0900
@@ -197,14 +197,14 @@
         except Exception, err:
             raise PycodeError('error importing %r' % modname, err)
     mod = sys.modules[modname]
-    if hasattr(mod, '__loader__'):
-        try:
-            source = mod.__loader__.get_source(modname)
-        except Exception, err:
-            raise PycodeError('error getting source for %r' % modname, err)
-        return 'string', source
     filename = getattr(mod, '__file__', None)
     if filename is None:
+        if hasattr(mod, '__loader__'):
+            try:
+                source = mod.__loader__.get_source(modname)
+            except Exception, err:
+                raise PycodeError('error getting source for %r' % modname, err)
+            return 'string', source
         raise PycodeError('no source found for module %r' % modname)
     filename = path.normpath(path.abspath(filename))
     lfilename = filename.lower()