diff --git a/services/URIBeacon2Service.h b/services/URIBeacon2Service.h
index bf5926b..074009f 100644
--- a/services/URIBeacon2Service.h
+++ b/services/URIBeacon2Service.h
@@ -342,7 +342,7 @@ private:
     }
 
 private:
-    static const size_t MAX_SIZEOF_SERVICE_DATA_PAYLOAD = 27;
+    static const size_t MAX_SIZEOF_SERVICE_DATA_PAYLOAD = 18; /* Uri Data must be between 0 and 18 bytes in length. */
     static const size_t MAX_SIZE_URI_DATA_CHAR_VALUE    = 48;
 
 private: