diff --git a/src/event/cloudevent.ts b/src/event/cloudevent.ts
index 4cc7fcb..0cab0da 100644
--- a/src/event/cloudevent.ts
+++ b/src/event/cloudevent.ts
@@ -9,7 +9,7 @@ import {
   CloudEventV1OptionalAttributes,
 } from "./interfaces";
 import { validateV1, validateV03 } from "./spec";
-import { ValidationError, isBinary, asBase64 } from "./validation";
+import { ValidationError, isBinary, asBase64, isValidType } from "./validation";
 import CONSTANTS from "../constants";
 import { isString } from "util";
 
@@ -108,6 +108,13 @@ export class CloudEvent implements CloudEventV1, CloudEventV03 {
       if (!key.match(/^[a-z0-9]{1,20}$/)) {
         throw new ValidationError("invalid extension name");
       }
+
+      // Value should be spec compliant
+      // https://github.com/cloudevents/spec/blob/master/spec.md#type-system
+      if (!isValidType(value)) {
+        throw new ValidationError("invalid extension value");
+      }
+
       this[key] = value;
     }
 
diff --git a/src/event/validation.ts b/src/event/validation.ts
index 56b97e5..6ca0258 100644
--- a/src/event/validation.ts
+++ b/src/event/validation.ts
@@ -81,5 +81,5 @@ export const asData = (data: unknown, contentType: string): string => {
   return isBinary(maybeJson) ? asBase64(maybeJson) : maybeJson;
 };
 
-export const isValidType = (v: boolean | number | string | Date | Uint32Array): boolean =>
-  isBoolean(v) || isInteger(v) || isString(v) || isDate(v) || isBinary(v);
+export const isValidType = (v: boolean | number | string | Date | Uint32Array | unknown): boolean =>
+  isBoolean(v) || isInteger(v) || isString(v) || isDate(v) || isBinary(v) || isObject(v);
diff --git a/test/integration/http_emitter_test.ts b/test/integration/http_emitter_test.ts
index 1644af9..b5f211b 100644
--- a/test/integration/http_emitter_test.ts
+++ b/test/integration/http_emitter_test.ts
@@ -15,6 +15,8 @@ const ext1Name = "lunch";
 const ext1Value = "tacos";
 const ext2Name = "supper";
 const ext2Value = "sushi";
+const ext3Name = "snack";
+const ext3Value = { value: "chips" };
 
 const data = {
   lunchBreak: "noon",
@@ -45,6 +47,7 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
       data,
       [ext1Name]: ext1Value,
       [ext2Name]: ext2Value,
+      [ext3Name]: ext3Value,
     });
 
     it("Sends a binary 1.0 CloudEvent by default", () => {
@@ -59,6 +62,7 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
           // Ensure extensions are handled properly
           expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext1Name}`]).to.equal(ext1Value);
           expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext2Name}`]).to.equal(ext2Value);
+          expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext3Name}`].value).to.equal(ext3Value.value);
         })
         .catch(expect.fail);
     });
@@ -142,6 +146,7 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
       data,
       [ext1Name]: ext1Value,
       [ext2Name]: ext2Value,
+      [ext3Name]: ext3Value,
     });
 
     it("Sends a binary 0.3 CloudEvent", () => {
@@ -156,6 +161,7 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
           // Ensure extensions are handled properly
           expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext1Name}`]).to.equal(ext1Value);
           expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext2Name}`]).to.equal(ext2Value);
+          expect(response.data[`${CONSTANTS.EXTENSIONS_PREFIX}${ext3Name}`].value).to.equal(ext3Value.value);
         })
         .catch(expect.fail);
     });
diff --git a/test/integration/spec_1_tests.ts b/test/integration/spec_1_tests.ts
index d580283..e39d3a5 100644
--- a/test/integration/spec_1_tests.ts
+++ b/test/integration/spec_1_tests.ts
@@ -87,13 +87,13 @@ describe("CloudEvents Spec v1.0", () => {
       expect(cloudevent.cloneWith({ extdate: myDate }).validate()).to.equal(true);
     });
 
-    // even though the spec doesn't allow object types for
-    // extensions, it could be JSON. And before a JS CE
-    // is transmitted across the wire, this value will be
-    // converted to JSON
     it("should be ok when the type is an object", () => {
       expect(cloudevent.cloneWith({ objectextension: { some: "object" } }).validate()).to.equal(true);
     });
+
+    it("should be ok when the type is an string converted from an object", () => {
+      expect(cloudevent.cloneWith({ objectextension: JSON.stringify({ some: "object" }) }).validate()).to.equal(true);
+    });
   });
 
   describe("The Constraints check", () => {