diff --git a/contrib/linearize/example-linearize.cfg b/contrib/linearize/example-linearize.cfg
index e0fef1388..38da02e66 100644
--- a/contrib/linearize/example-linearize.cfg
+++ b/contrib/linearize/example-linearize.cfg
@@ -4,13 +4,23 @@ rpcuser=someuser
 rpcpassword=somepassword
 host=127.0.0.1
 port=8332
+#port=18332
 
 # bootstrap.dat hashlist settings (linearize-hashes)
 max_height=313000
 
 # bootstrap.dat input/output settings (linearize-data)
+
+# mainnet
 netmagic=f9beb4d9
+genesis=000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
 input=/home/example/.bitcoin/blocks
+
+# testnet
+#netmagic=0b110907
+#genesis=000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943
+#input=/home/example/.bitcoin/testnet3/blocks
+
 output_file=/home/example/Downloads/bootstrap.dat
 hashlist=hashlist.txt
 split_year=1
diff --git a/contrib/linearize/linearize-data.py b/contrib/linearize/linearize-data.py
index a3a1173b1..7947c6bf7 100755
--- a/contrib/linearize/linearize-data.py
+++ b/contrib/linearize/linearize-data.py
@@ -205,7 +205,7 @@ class BlockDataCopier:
 
 			inMagic = inhdr[:4]
 			if (inMagic != self.settings['netmagic']):
-				print("Invalid magic: " + inMagic)
+				print("Invalid magic: " + inMagic.encode('hex'))
 				return
 			inLenLE = inhdr[4:]
 			su = struct.unpack("<I", inLenLE)
@@ -265,6 +265,8 @@ if __name__ == '__main__':
 
 	if 'netmagic' not in settings:
 		settings['netmagic'] = 'f9beb4d9'
+	if 'genesis' not in settings:
+		settings['genesis'] = '000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f'
 	if 'input' not in settings:
 		settings['input'] = 'input'
 	if 'hashlist' not in settings:
@@ -291,7 +293,7 @@ if __name__ == '__main__':
 	blkindex = get_block_hashes(settings)
 	blkmap = mkblockmap(blkindex)
 
-	if not "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f" in blkmap:
+	if not settings['genesis'] in blkmap:
 		print("Genesis block not found in hashlist")
 	else:
 		BlockDataCopier(settings, blkindex, blkmap).run()