diff --git a/src/infuse_iot/cpatch.py b/src/infuse_iot/cpatch.py
index e032c5b..0fc1c15 100644
--- a/src/infuse_iot/cpatch.py
+++ b/src/infuse_iot/cpatch.py
@@ -506,7 +506,7 @@ def _naive_diff(cls, old: bytes, new: bytes, hash_len: int = 8):
         # Pre-hash original image
         pre_hash = {}
         prev_val = None
-        for offset in range(len(old) - hash_len):
+        for offset in range(len(old) - hash_len + 1):
             val = old[offset : offset + hash_len]
             if val == prev_val:
                 continue