diff --git a/README.md b/README.md
index 63dbb72..afc99c3 100644
--- a/README.md
+++ b/README.md
@@ -120,6 +120,11 @@ var config = {
   url   : "https://myserver.com"
 };
 
+/*
+ * To use HTTP Binary:
+ *   Cloudevent.bindings["http-binary0.2"](config);
+ */
+
 // The binding instance
 var binding = Cloudevent.bindings["http-structured0.1"](config);
 
diff --git a/ext/spec_0_2.json b/ext/spec_0_2.json
index aa892a1..2848dc0 100644
--- a/ext/spec_0_2.json
+++ b/ext/spec_0_2.json
@@ -32,6 +32,9 @@
         "time": {
           "$ref": "#/definitions/time"
         },
+        "schemaurl": {
+          "$ref": "#/definitions/schemaurl"
+        },
         "type": {
           "$ref": "#/definitions/type"
         },
@@ -58,6 +61,10 @@
       "format": "date-time",
       "type": "string"
     },
+    "schemaurl": {
+      "type": "string",
+      "format": "uri"
+    },
     "type": {
       "type": "string",
       "minLength": 1
diff --git a/lib/specs/spec_0_2.js b/lib/specs/spec_0_2.js
index 7dc29c8..ac105b7 100644
--- a/lib/specs/spec_0_2.js
+++ b/lib/specs/spec_0_2.js
@@ -16,8 +16,9 @@ const reserved = {
 
 const schema = require("../../ext/spec_0_2.json");
 
-// Default options
-const ajv = new Ajv();
+const ajv = new Ajv({
+  extendRefs: true //  validate all keywords in the schemas with $ref (the default behaviour in versions before 5.0.0)
+});
 
 const validate = ajv.compile(schema);
 
@@ -36,7 +37,7 @@ Spec02.prototype.check = function(){
   var valid = validate(this.payload);
 
   if(!valid) {
-    throw {message: "invalid payload"};
+    throw {message: "invalid payload", errors: validate.errors};
   }
 
 };
diff --git a/test/cloudevent_spec_0_2.js b/test/cloudevent_spec_0_2.js
index bdfbb16..212cd04 100644
--- a/test/cloudevent_spec_0_2.js
+++ b/test/cloudevent_spec_0_2.js
@@ -40,6 +40,14 @@ describe("CloudEvents Spec 0.2 - JavaScript SDK", () => {
         expect(cloudevent.format()).to.have.property("specversion");
       });
 
+      it("should throw an error when mandatory attribute is absent", () => {
+        delete cloudevent.spec.payload.source;
+        expect(cloudevent.format.bind(cloudevent))
+          .to
+          .throw("invalid payload");
+        cloudevent.spec.payload.source = source;
+      });
+
       it("requires 'source'", () => {
         expect(cloudevent.format()).to.have.property("source");
       });
@@ -60,6 +68,14 @@ describe("CloudEvents Spec 0.2 - JavaScript SDK", () => {
         expect(cloudevent.format()).to.have.property("schemaurl");
       });
 
+      it("should throw an error when 'schemaurl' is not an URI", () => {
+        cloudevent.spec.payload.schemaurl = "KKKKKK";
+        expect(cloudevent.format.bind(cloudevent))
+          .to
+          .throw("invalid payload");
+        cloudevent.spec.payload.schemaurl = schemaurl;
+      });
+
       it("contains 'contenttype'", () => {
         cloudevent.contenttype(contenttype);
         expect(cloudevent.format()).to.have.property("contenttype");