diff --git a/amodem/framing.py b/amodem/framing.py
index 1b1027c..62dedf1 100644
--- a/amodem/framing.py
+++ b/amodem/framing.py
@@ -26,8 +26,10 @@ class Checksum(object):
         payload = data[self.size:]
         expected = _checksum_func(payload)
         if received != expected:
-            log.warning('Invalid checksum: %04x != %04x', received, expected)
+            log.warning('Invalid checksum: %08x != %08x', received, expected)
             raise ValueError('Invalid checksum')
+        else:
+            log.debug('Good checksum: %08x', received)
         return payload