diff -r b392a39970bb Lib/json/decoder.py
--- a/Lib/json/decoder.py	Sun Sep 30 22:48:20 2012 +0300
+++ b/Lib/json/decoder.py	Thu Oct 04 16:32:59 2012 +0200
@@ -367,5 +367,6 @@
         try:
             obj, end = self.scan_once(s, idx)
         except StopIteration:
-            raise ValueError("No JSON object could be decoded")
+            raise ValueError("No JSON object could be decoded"
+                             " from {}".format(repr(s)))
         return obj, end