diff --git a/electrum/blockchain.py b/electrum/blockchain.py
index f911d4b1e..9e9944902 100644
--- a/electrum/blockchain.py
+++ b/electrum/blockchain.py
@@ -37,7 +37,9 @@ from .logging import get_logger, Logger
 _logger = get_logger(__name__)
 
 HEADER_SIZE = 80  # bytes
-MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
+
+# see https://github.com/bitcoin/bitcoin/blob/feedb9c84e72e4fff489810a2bbeec09bcda5763/src/chainparams.cpp#L76
+MAX_TARGET = 0x00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff  # compact: 0x1d00ffff
 
 
 class MissingHeader(Exception):