diff --git a/types/passport-http/index.d.ts b/types/passport-http/index.d.ts
index 63527b6225..f872a7513b 100644
--- a/types/passport-http/index.d.ts
+++ b/types/passport-http/index.d.ts
@@ -3,6 +3,7 @@
 // Definitions by: Christophe Vidal <https://github.com/krizalys>
 //                 Tomek Łaziuk <https://github.com/tlaziuk>
 //                 Chris Barth <https://github.com/cjbarth>
+//                 James Adarich <https://github.com/jamesadarich>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -52,7 +53,7 @@ export type DigestValidateFunction = (
     done: (error: any, valid: boolean) => void,
 ) => any;
 
-export class BasicStrategy extends passport.Strategy {
+export class BasicStrategy implements passport.Strategy {
     constructor(verify: BasicVerifyFunction);
     constructor(options: BasicStrategyOptions<false>, verify: BasicVerifyFunction);
     constructor(options: BasicStrategyOptions<true>, verify: BasicVerifyFunctionWithRequest);
@@ -61,7 +62,7 @@ export class BasicStrategy extends passport.Strategy {
     authenticate(req: express.Request, options?: object): void;
 }
 
-export class DigestStrategy extends passport.Strategy {
+export class DigestStrategy implements passport.Strategy {
     constructor(secret: DigestSecretFunction, validate?: DigestValidateFunction);
     constructor(options: DigestStrategyOptions, secret: DigestSecretFunction, validate?: DigestValidateFunction);