diff --git a/private/aws-protocoltests-ec2/test/functional/ec2query.spec.ts b/private/aws-protocoltests-ec2/test/functional/ec2query.spec.ts
index 6dc247056b7e..6517aad37a32 100644
--- a/private/aws-protocoltests-ec2/test/functional/ec2query.spec.ts
+++ b/private/aws-protocoltests-ec2/test/functional/ec2query.spec.ts
@@ -352,6 +352,9 @@ it("Ec2QueryEndpointTrait:Request", async () => {
     expect(r.headers["content-type"]).toBeDefined();
     expect(r.headers["content-type"]).toBe("application/x-www-form-urlencoded");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `Action=EndpointOperation&Version=2020-01-08`;
@@ -391,6 +394,9 @@ it("Ec2QueryEndpointTraitWithHostLabel:Request", async () => {
     expect(r.headers["content-type"]).toBeDefined();
     expect(r.headers["content-type"]).toBe("application/x-www-form-urlencoded");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `Action=EndpointWithHostLabelOperation&Version=2020-01-08&Label=bar`;
diff --git a/private/aws-protocoltests-json-10/test/functional/awsjson1_0.spec.ts b/private/aws-protocoltests-json-10/test/functional/awsjson1_0.spec.ts
index 943d1bc03f68..a1e472c9d7e1 100644
--- a/private/aws-protocoltests-json-10/test/functional/awsjson1_0.spec.ts
+++ b/private/aws-protocoltests-json-10/test/functional/awsjson1_0.spec.ts
@@ -252,6 +252,9 @@ it("AwsJson10EndpointTrait:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `{}`;
@@ -288,6 +291,9 @@ it("AwsJson10EndpointTraitWithHostLabel:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `{\"label\": \"bar\"}`;
diff --git a/private/aws-protocoltests-json/test/functional/awsjson1_1.spec.ts b/private/aws-protocoltests-json/test/functional/awsjson1_1.spec.ts
index d485b5682563..b93a093a4b36 100644
--- a/private/aws-protocoltests-json/test/functional/awsjson1_1.spec.ts
+++ b/private/aws-protocoltests-json/test/functional/awsjson1_1.spec.ts
@@ -477,6 +477,9 @@ it("AwsJson11EndpointTrait:Request", async () => {
     expect(r.headers["x-amz-target"]).toBeDefined();
     expect(r.headers["x-amz-target"]).toBe("JsonProtocol.EndpointOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `{}`;
@@ -518,6 +521,9 @@ it("AwsJson11EndpointTraitWithHostLabel:Request", async () => {
     expect(r.headers["x-amz-target"]).toBeDefined();
     expect(r.headers["x-amz-target"]).toBe("JsonProtocol.EndpointWithHostLabelOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `{\"label\": \"bar\"}`;
diff --git a/private/aws-protocoltests-query/test/functional/awsquery.spec.ts b/private/aws-protocoltests-query/test/functional/awsquery.spec.ts
index 1a956a87553d..e112df05b4a9 100644
--- a/private/aws-protocoltests-query/test/functional/awsquery.spec.ts
+++ b/private/aws-protocoltests-query/test/functional/awsquery.spec.ts
@@ -352,6 +352,9 @@ it("AwsQueryEndpointTrait:Request", async () => {
     expect(r.headers["content-type"]).toBeDefined();
     expect(r.headers["content-type"]).toBe("application/x-www-form-urlencoded");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `Action=EndpointOperation&Version=2020-01-08`;
@@ -391,6 +394,9 @@ it("AwsQueryEndpointTraitWithHostLabel:Request", async () => {
     expect(r.headers["content-type"]).toBeDefined();
     expect(r.headers["content-type"]).toBe("application/x-www-form-urlencoded");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `Action=EndpointWithHostLabelOperation&Version=2020-01-08&label=bar`;
diff --git a/private/aws-protocoltests-restjson/test/functional/restjson1.spec.ts b/private/aws-protocoltests-restjson/test/functional/restjson1.spec.ts
index 4695682c295b..ee1840bcb94e 100644
--- a/private/aws-protocoltests-restjson/test/functional/restjson1.spec.ts
+++ b/private/aws-protocoltests-restjson/test/functional/restjson1.spec.ts
@@ -1634,6 +1634,9 @@ it("RestJsonEndpointTrait:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/EndpointOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeFalsy();
   }
 });
@@ -1666,6 +1669,9 @@ it("RestJsonEndpointTraitWithHostLabel:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/EndpointWithHostLabelOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `{\"label\": \"bar\"}`;
diff --git a/private/aws-protocoltests-restxml/test/functional/restxml.spec.ts b/private/aws-protocoltests-restxml/test/functional/restxml.spec.ts
index 40428016e0a4..0ad931b3f8fb 100644
--- a/private/aws-protocoltests-restxml/test/functional/restxml.spec.ts
+++ b/private/aws-protocoltests-restxml/test/functional/restxml.spec.ts
@@ -888,6 +888,9 @@ it("RestXmlEndpointTrait:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/EndpointOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.example.com");
+
     expect(r.body).toBeFalsy();
   }
 });
@@ -925,6 +928,9 @@ it("RestXmlEndpointTraitWithHostLabelAndHttpBinding:Request", async () => {
     expect(r.headers["x-amz-account-id"]).toBeDefined();
     expect(r.headers["x-amz-account-id"]).toBe("bar");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("bar.example.com");
+
     expect(r.body).toBeFalsy();
   }
 });
@@ -957,6 +963,9 @@ it("RestXmlEndpointTraitWithHostLabel:Request", async () => {
     expect(r.method).toBe("POST");
     expect(r.path).toBe("/EndpointWithHostLabelOperation");
 
+    expect(r.headers["host"]).toBeDefined();
+    expect(r.headers["host"]).toBe("foo.bar.example.com");
+
     expect(r.body).toBeDefined();
     const utf8Encoder = client.config.utf8Encoder;
     const bodyString = `<EndpointWithHostLabelOperationRequest>
diff --git a/scripts/generate-clients/config.js b/scripts/generate-clients/config.js
index 84470d9cda45..2891e5934407 100644
--- a/scripts/generate-clients/config.js
+++ b/scripts/generate-clients/config.js
@@ -1,7 +1,7 @@
 // Update this commit when taking up new changes from smithy-typescript.
 module.exports = {
   // Use full commit hash as we explicitly fetch it.
-  SMITHY_TS_COMMIT: "cf9d6fe3483ba027f98e87d1921c32dd94e2c1f9",
+  SMITHY_TS_COMMIT: "78cb9a8fa99a2983d44e63f13266f093dacde90a",
 };
 
 if (module.exports.SMITHY_TS_COMMIT.length < 40) {