diff --git a/lib/net/parser.js b/lib/net/parser.js
index 9fd3eda3..f20a13e9 100644
--- a/lib/net/parser.js
+++ b/lib/net/parser.js
@@ -103,7 +103,7 @@ Parser.prototype.parse = function parse(data) {
   if (checksum !== this.header.checksum) {
     this.waiting = 24;
     this.header = null;
-    this.error('Invalid checksum: %d.', util.hex32(checksum));
+    this.error('Invalid checksum: %s.', util.hex32(checksum));
     return;
   }