diff --git a/src/lib/middleware/framework-services/express.ts b/src/lib/middleware/framework-services/express.ts
index 46f48e3..8d29414 100644
--- a/src/lib/middleware/framework-services/express.ts
+++ b/src/lib/middleware/framework-services/express.ts
@@ -2,7 +2,7 @@ import { FrameworkService } from "../interfaces";
 
 export default class ExpressService implements FrameworkService {
 
-    getReqHeaderField(req: any, fieldName: string): string {
+    getReqHeaderField(req: any, fieldName: string): string | undefined {
         return req.header(fieldName);
     }
 
@@ -30,7 +30,7 @@ export default class ExpressService implements FrameworkService {
         return value
     }
 
-    getResHeaderField(res: any, fieldName: string): string {
+    getResHeaderField(res: any, fieldName: string): string | undefined {
         return res.get(fieldName);
     }
 
diff --git a/src/lib/middleware/framework-services/fastify.ts b/src/lib/middleware/framework-services/fastify.ts
index 426780a..1f5ac40 100644
--- a/src/lib/middleware/framework-services/fastify.ts
+++ b/src/lib/middleware/framework-services/fastify.ts
@@ -2,8 +2,8 @@ import { FrameworkService } from "../interfaces";
 
 export default class FastifyService implements FrameworkService {
 
-    getReqHeaderField(req: any, fieldName: string): string {
-        return req.headers[fieldName] ? req.headers[fieldName] : ""
+    getReqHeaderField(req: any, fieldName: string): string | undefined {
+        return req.headers[fieldName]
     }
 
     getReqField(req: any, fieldName: string): any {
@@ -31,8 +31,7 @@ export default class FastifyService implements FrameworkService {
     }
 
     getResHeaderField(res: any, fieldName: string): string {
-        let value = res.getHeader(fieldName)
-        return value ? value : "";
+        return res.getHeader(fieldName)
     }
 
     getResField(res: any, fieldName: string): any {
diff --git a/src/lib/middleware/framework-services/plainhttp.ts b/src/lib/middleware/framework-services/plainhttp.ts
index 0266d23..00abf2e 100644
--- a/src/lib/middleware/framework-services/plainhttp.ts
+++ b/src/lib/middleware/framework-services/plainhttp.ts
@@ -31,7 +31,7 @@ export default class HttpService implements FrameworkService {
     }
 
     getResHeaderField(res: any, fieldName: string): string {
-        return res.getHeader ? res.getHeader(fieldName) : "";
+        return res.getHeader ? res.getHeader(fieldName) : undefined;
     }
 
     getResField(res: any, fieldName: string): any {
diff --git a/src/lib/middleware/framework-services/restify.ts b/src/lib/middleware/framework-services/restify.ts
index 8855668..543a1bd 100644
--- a/src/lib/middleware/framework-services/restify.ts
+++ b/src/lib/middleware/framework-services/restify.ts
@@ -31,7 +31,7 @@ export default class RestifyService implements FrameworkService {
     }
 
     getResHeaderField(res: any, fieldName: string): string {
-        return res.get ? res.get(fieldName) : "";
+        return res.get ? res.get(fieldName) : undefined;
     }
 
     getResField(res: any, fieldName: string): any {
diff --git a/src/lib/middleware/interfaces.ts b/src/lib/middleware/interfaces.ts
index 53b9533..80017c4 100644
--- a/src/lib/middleware/interfaces.ts
+++ b/src/lib/middleware/interfaces.ts
@@ -1,7 +1,7 @@
 export interface FrameworkService {
-    getReqHeaderField(req: any, fieldName: string): string;
+    getReqHeaderField(req: any, fieldName: string): string | undefined;
     getReqField(req: any, fieldName: string): string | number | boolean | undefined;
-    getResHeaderField(req: any, fieldName: string): string;
+    getResHeaderField(req: any, fieldName: string): string | undefined;
     getResField(req: any, fieldName: string): string | number | boolean | undefined;
     onResFinish(res: any, handler: () => void): undefined;
 }
diff --git a/src/lib/middleware/requestAccessor.ts b/src/lib/middleware/requestAccessor.ts
index 2d17d16..2d6c044 100644
--- a/src/lib/middleware/requestAccessor.ts
+++ b/src/lib/middleware/requestAccessor.ts
@@ -16,7 +16,7 @@ export default class RequestAccessor {
         return RequestAccessor.instance;
     }
 
-    getHeaderField(req: any, fieldName: string): string {
+    getHeaderField(req: any, fieldName: string): string | undefined {
         return this.frameworkService.getReqHeaderField(req, fieldName);
     }
 
diff --git a/src/lib/middleware/responseAccessor.ts b/src/lib/middleware/responseAccessor.ts
index d1a3172..425eb0e 100644
--- a/src/lib/middleware/responseAccessor.ts
+++ b/src/lib/middleware/responseAccessor.ts
@@ -16,7 +16,7 @@ export default class ResponseAccessor {
         return ResponseAccessor.instance;
     }
 
-    getHeaderField(res: any, fieldName: string): string {
+    getHeaderField(res: any, fieldName: string): string | undefined {
         return this.frameworkService.getResHeaderField(res, fieldName);
     }