diff --git a/packages/binding-http/src/http-server.ts b/packages/binding-http/src/http-server.ts
index 74a86626b..17ea7a42d 100644
--- a/packages/binding-http/src/http-server.ts
+++ b/packages/binding-http/src/http-server.ts
@@ -375,7 +375,7 @@ export default class HttpServer implements ProtocolServer {
                     form,
                     (tdTemplate.properties?.[propertyName] ?? {}) as PropertyElement
                 );
-                if (thing.properties[propertyName].readOnl === true) {
+                if (thing.properties[propertyName].readOnly === true) {
                     form.op = ["readproperty"];
                     const hform: HttpForm = form;
                     if (hform["htv:methodName"] === undefined) {