diff --git a/monero_serialize/xmrboost.py b/monero_serialize/xmrboost.py
index <HASH>..<HASH> 100644
--- a/monero_serialize/xmrboost.py
+++ b/monero_serialize/xmrboost.py
@@ -32,6 +32,9 @@ async def load_uvarint(reader):
     result = 0
     shift = 0
 
+    if size > 8:
+        raise ValueError('Varint size too big')
+
     # TODO: endianity, rev bytes if needed
     for _ in range(size):
         await reader.areadinto(buffer)
boost: varint unserialize range check

- too big varint is probably an invalid deserialization, maximum allowed is 8 B