diff -ur old/inspect.py new/inspect.py
--- old/inspect.py	2013-03-25 21:26:37.000000000 -0700
+++ new/inspect.py	2013-03-25 21:26:54.000000000 -0700
@@ -550,7 +550,7 @@
 
     file = getfile(object)
     sourcefile = getsourcefile(object)
-    if not sourcefile and file[0] + file[-1] != '<>':
+    if not sourcefile and (not file or file[0] + file[-1] != '<>'):
         raise IOError('source code not available')
     file = sourcefile if sourcefile else file
 
diff -ur old/test_inspect.py new/test_inspect.py
--- old/test_inspect.py	2013-03-25 21:22:58.000000000 -0700
+++ new/test_inspect.py	2013-03-25 21:23:58.000000000 -0700
@@ -416,6 +416,11 @@
         finally:
             del linecache.cache[co.co_filename]
 
+    def test_findsource_empty_filename(self):
+        lines = ["x=1"]
+        co = compile(lines[0], "", "exec")
+        self.assertRaises(IOError, inspect.findsource, co)
+
 class TestNoEOL(GetSourceBase):
     def __init__(self, *args, **kwargs):
         self.tempdir = TESTFN + '_dir'