diff --git a/src/event/cloudevent.ts b/src/event/cloudevent.ts
index ecacbfb..93516e2 100644
--- a/src/event/cloudevent.ts
+++ b/src/event/cloudevent.ts
@@ -96,6 +96,11 @@ export class CloudEvent implements CloudEventV1, CloudEventV03 {
 
     // finally process any remaining properties - these are extensions
     for (const [key, value] of Object.entries(properties)) {
+      // Extension names should only allow lowercase a-z and 0-9 in the name
+      // names should not exceed 20 characters in length
+      if (!key.match(/^[a-z0-9]{1,20}$/)) {
+        throw new ValidationError("invalid extension name");
+      }
       this[key] = value;
     }
 
diff --git a/test/integration/cloud_event_test.ts b/test/integration/cloud_event_test.ts
index 6ea0645..8a98a62 100644
--- a/test/integration/cloud_event_test.ts
+++ b/test/integration/cloud_event_test.ts
@@ -25,6 +25,18 @@ describe("A CloudEvent", () => {
     const ce = new CloudEvent(fixture);
     expect(ce.toString()).to.deep.equal(JSON.stringify(ce));
   });
+
+  it("Throw a validation error for invalid extension names", () => {
+    expect(() => {
+      new CloudEvent({ "ext-1": "extension1", ...fixture });
+    }).throw("invalid extension name");
+  });
+
+  it("Throw a validation error for invalid extension names, more than 20 chars", () => {
+    expect(() => {
+      new CloudEvent({ "123456789012345678901": "extension1", ...fixture });
+    }).throw("invalid extension name");
+  });
 });
 
 describe("A 1.0 CloudEvent", () => {
@@ -92,13 +104,13 @@ describe("A 1.0 CloudEvent", () => {
 
   it("can be constructed with extensions", () => {
     const extensions = {
-      "extension-key": "extension-value",
+      extensionkey: "extension-value",
     };
     const ce = new CloudEvent({
       ...extensions,
       ...fixture,
     });
-    expect(ce["extension-key"]).to.equal(extensions["extension-key"]);
+    expect(ce["extensionkey"]).to.equal(extensions["extensionkey"]);
   });
 
   it("throws ValidationError if the CloudEvent does not conform to the schema");
diff --git a/test/integration/receiver_structured_1_test.ts b/test/integration/receiver_structured_1_test.ts
index 6e36809..250dab9 100644
--- a/test/integration/receiver_structured_1_test.ts
+++ b/test/integration/receiver_structured_1_test.ts
@@ -11,8 +11,6 @@ const source = "urn:event:from:myapi/resourse/123";
 const time = new Date();
 const dataschema = "http://cloudevents.io/schema.json";
 
-const ceContentType = "application/json";
-
 const data = {
   foo: "bar",
 };
@@ -108,7 +106,6 @@ describe("HTTP Transport Binding Structured Receiver for CloudEvents v1.0", () =
         time,
         data,
         dataschema,
-        dataContentType: ceContentType,
       };
       const headers = {
         "content-type": "application/cloudevents+json",
@@ -124,14 +121,13 @@ describe("HTTP Transport Binding Structured Receiver for CloudEvents v1.0", () =
 
     it("Should accept 'extension1'", () => {
       // setup
-      const extension1 = "mycustom-ext1";
+      const extension1 = "mycustomext1";
       const event = {
         type,
         source,
         time,
         data,
         dataschema,
-        dataContentType: ceContentType,
         extension1,
       };
 
@@ -152,7 +148,6 @@ describe("HTTP Transport Binding Structured Receiver for CloudEvents v1.0", () =
         time,
         dataschema,
         data: data,
-        dataContentType: ceContentType,
       };
 
       const headers = {
@@ -173,7 +168,6 @@ describe("HTTP Transport Binding Structured Receiver for CloudEvents v1.0", () =
         type,
         source,
         data: bindata,
-        dataContentType: ceContentType,
       };
 
       const headers = {
diff --git a/test/integration/spec_1_tests.ts b/test/integration/spec_1_tests.ts
index 47dd1b5..d580283 100644
--- a/test/integration/spec_1_tests.ts
+++ b/test/integration/spec_1_tests.ts
@@ -65,26 +65,26 @@ describe("CloudEvents Spec v1.0", () => {
 
   describe("Extensions Constraints", () => {
     it("should be ok when type is 'boolean'", () => {
-      expect(cloudevent.cloneWith({ "ext-boolean": true }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ extboolean: true }).validate()).to.equal(true);
     });
 
     it("should be ok when type is 'integer'", () => {
-      expect(cloudevent.cloneWith({ "ext-integer": 2019 }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ extinteger: 2019 }).validate()).to.equal(true);
     });
 
     it("should be ok when type is 'string'", () => {
-      expect(cloudevent.cloneWith({ "ext-string": "an-string" }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ extstring: "an-string" }).validate()).to.equal(true);
     });
 
     it("should be ok when type is 'Uint32Array' for 'Binary'", () => {
       const myBinary = new Uint32Array(2019);
-      expect(cloudevent.cloneWith({ "ext-binary": myBinary }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ extbinary: myBinary }).validate()).to.equal(true);
     });
 
     // URI
     it("should be ok when type is 'Date' for 'Timestamp'", () => {
       const myDate = new Date();
-      expect(cloudevent.cloneWith({ "ext-date": myDate }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ extdate: myDate }).validate()).to.equal(true);
     });
 
     // even though the spec doesn't allow object types for
@@ -92,7 +92,7 @@ describe("CloudEvents Spec v1.0", () => {
     // 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({ "object-extension": { some: "object" } }).validate()).to.equal(true);
+      expect(cloudevent.cloneWith({ objectextension: { some: "object" } }).validate()).to.equal(true);
     });
   });