--- a/Lib/importlib/abc.py	Wed Jun 27 15:26:26 2012 -0400
+++ b/Lib/importlib/abc.py	Thu Jun 28 08:37:44 2012 -0700
@@ -282,7 +282,11 @@
                 if len(raw_timestamp) < 4:
                     raise EOFError("bad timestamp in {}".format(fullname))
                 pyc_timestamp = _bootstrap._r_long(raw_timestamp)
-                bytecode = data[8:]
+                raw_file_size = data[8:12]
+                if len(raw_file_size) < 4:
+                    raise EOFError("bad file size in {}".format(fullname))
+                file_size = _bootstrap._r_long(raw_file_size)
+                bytecode = data[12:]
                 # Verify that the magic number is valid.
                 if imp.get_magic() != magic:
                     raise ImportError(
@@ -316,9 +320,11 @@
         code_object = compile(source, source_path, 'exec', dont_inherit=True)
         # Generate bytecode and write it out.
         if not sys.dont_write_bytecode:
+            bytecode = marshal.dumps(code_object)
             data = bytearray(imp.get_magic())
             data.extend(_bootstrap._w_long(source_timestamp))
-            data.extend(marshal.dumps(code_object))
+            data.extend(_bootstrap._w_long(len(source)))
+            data.extend(bytecode)
             self.write_bytecode(fullname, data)
         return code_object