diff --git a/chapter2.md b/chapter2.md
index 7cd02f5..84b80db 100644
--- a/chapter2.md
+++ b/chapter2.md
@@ -57,7 +57,7 @@ We'll also need a function for writing query names in labeled form:
     fn write_qname(&mut self, qname: &str) -> Result<()> {
         for label in qname.split('.') {
             let len = label.len();
-            if len > 0x34 {
+            if len > 0x3f {
                 return Err("Single label exceeds 63 characters of length".into());
             }