diff --git a/ledgerblue/hexLoader.py b/ledgerblue/hexLoader.py
index de461a7..3281ae8 100644
--- a/ledgerblue/hexLoader.py
+++ b/ledgerblue/hexLoader.py
@@ -311,13 +311,13 @@ class HexLoader:
 		bootadr |= 1
 		data = b'\x09' + struct.pack('>I', bootadr)
 		if (signature != None):
-			data += chr(len(signature)) + signature
+			data += struct.pack('>B', len(signature)) + signature
 		self.exchange(self.cla, 0x00, 0x00, 0x00, data)
 
 	def commit(self, signature=None):
 		data = b'\x09'
 		if (signature != None):
-			data += chr(len(signature)) + signature
+			data += struct.pack('>B', len(signature)) + signature
 		self.exchange(self.cla, 0x00, 0x00, 0x00, data)
 
 	def createAppNoInstallParams(self, appflags, applength, appname, icon=None, path=None, iconOffset=None, iconSize=None, appversion=None):
diff --git a/ledgerblue/loadApp.py b/ledgerblue/loadApp.py
index fcdc76a..2d8d065 100644
--- a/ledgerblue/loadApp.py
+++ b/ledgerblue/loadApp.py
@@ -56,12 +56,13 @@ def auto_int(x):
 	return int(x, 0)
 
 def parse_bip32_path(path, apilevel):
+		import struct
 		if len(path) == 0:
 				return b""
 		result = b""
 		elements = path.split('/')
 		if apilevel >= 5:
-			result = result + chr(len(elements))
+			result = result + struct.pack('>B', len(elements))
 		for pathElement in elements:
 				element = pathElement.split('\'')
 				if len(element) == 1: