diff --git a/src/WorkflowStep.spec.ts b/src/WorkflowStep.spec.ts
index 7db5363a3..98928c565 100644
--- a/src/WorkflowStep.spec.ts
+++ b/src/WorkflowStep.spec.ts
@@ -96,7 +96,7 @@ describe('WorkflowStep', () => {
       const { validate } = await importWorkflowStep();
 
       // intentionally casting to string to trigger failure
-      const badId = {} as string;
+      const badId: string = {};
       const validationFn = () => validate(badId, MOCK_CONFIG_SINGLE);
 
       const expectedMsg = 'WorkflowStep expects a callback_id as the first argument';
diff --git a/src/receivers/ExpressReceiver.spec.ts b/src/receivers/ExpressReceiver.spec.ts
index 4ab419009..02c617110 100644
--- a/src/receivers/ExpressReceiver.spec.ts
+++ b/src/receivers/ExpressReceiver.spec.ts
@@ -267,14 +267,14 @@ describe('ExpressReceiver', function () {
       it('should handle valid requests', async () => {
         // Arrange
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const req = { body: { ssl_check: 1 } } as Request;
+        const req: Request = { body: { ssl_check: 1 } };
         let sent = false;
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const resp = {
+        const resp: Response = {
           send: () => {
             sent = true;
           },
-        } as Response;
+        };
         let errorResult: any;
         const next = (error: any) => {
           errorResult = error;
@@ -291,14 +291,14 @@ describe('ExpressReceiver', function () {
       it('should work with other requests', async () => {
         // Arrange
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const req = { body: { type: 'block_actions' } } as Request;
+        const req: Request = { body: { type: 'block_actions' } };
         let sent = false;
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const resp = {
+        const resp: Response = {
           send: () => {
             sent = true;
           },
-        } as Response;
+        };
         let errorResult: any;
         const next = (error: any) => {
           errorResult = error;
@@ -317,14 +317,14 @@ describe('ExpressReceiver', function () {
       it('should handle valid requests', async () => {
         // Arrange
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const req = { body: { type: 'url_verification', challenge: 'this is it' } } as Request;
+        const req: Request = { body: { type: 'url_verification', challenge: 'this is it' } };
         let sentBody = undefined;
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const resp = {
+        const resp: Response = {
           json: (body) => {
             sentBody = body;
           },
-        } as Response;
+        };
         let errorResult: any;
         const next = (error: any) => {
           errorResult = error;
@@ -341,14 +341,14 @@ describe('ExpressReceiver', function () {
       it('should work with other requests', async () => {
         // Arrange
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const req = { body: { ssl_check: 1 } } as Request;
+        const req: Request = { body: { ssl_check: 1 } };
         let sentBody = undefined;
         // tslint:disable-next-line: no-object-literal-type-assertion
-        const resp = {
+        const resp: Response = {
           json: (body) => {
             sentBody = body;
           },
-        } as Response;
+        };
         let errorResult: any;
         const next = (error: any) => {
           errorResult = error;