diff --git a/Lib/tokenize.py b/Lib/tokenize.py
index 9322e0f..1c93944 100644
--- a/Lib/tokenize.py
+++ b/Lib/tokenize.py
@@ -50,7 +50,7 @@
 Ignore = Whitespace + any(r'\\\r?\n' + Whitespace) + maybe(Comment)
 Name = r'[a-zA-Z_]\w*'
 
-Hexnumber = r'0[xX][\da-fA-F]*[lL]?'
+Hexnumber = r'0[xX][\da-fA-F]+[lL]?'
 Octnumber = r'0[0-7]*[lL]?'
 Decnumber = r'[1-9]\d*[lL]?'
 Intnumber = group(Hexnumber, Octnumber, Decnumber)