diff --git a/API.paw b/API.paw
index 4afa3fe93f8591081892b1502dabbde6a636f089..071cb5ae605066d9cf7866994ea3bb596249d413 100644
Binary files a/API.paw and b/API.paw differ
diff --git a/src/controller/BaseController.ts b/src/controller/BaseController.ts
index 76e707156b7ac734a38fc97e42aca4a95c2722b1..69a151758296662751a51db0f1c75f3438a56b90 100644
--- a/src/controller/BaseController.ts
+++ b/src/controller/BaseController.ts
@@ -17,4 +17,10 @@ export default class BaseController {
         return mementoDate;
     }
 
+    setMementoHeaderIfNecessary(date: Date | undefined, response: Response): void {
+        if(date) {
+            response.setHeader("Memento-Datetime", date.toISOString());
+        }
+    }
+
 }
\ No newline at end of file
diff --git a/src/controller/ComponentController.ts b/src/controller/ComponentController.ts
index 449fc88abc95d4fa3386425b70a842499cca96fa..b6f260a83712415bdcef3561ec462c263e6b46dd 100644
--- a/src/controller/ComponentController.ts
+++ b/src/controller/ComponentController.ts
@@ -38,13 +38,16 @@ export default class ComponentController extends BaseController {
             return;
         }
 
-        Component.findById(request.params.componentId, this.componentRepository, this.getMementoDate(request)).then(async (component) => {
+        const mementoDate: Date | undefined = this.getMementoDate(request);
+
+        Component.findById(request.params.componentId, this.componentRepository, mementoDate).then(async (component) => {
             if(component) {
                 const componentJsonLd = component.toJSONLD();
                 this.setJSONLDResponseType(response);
                 response.send(componentJsonLd);
             } else {
                 response.status(404);
+                this.setMementoHeaderIfNecessary(mementoDate, response);
                 this.setJSONLDResponseType(response);
                 response.send(new APIError("Component not found."));
             }
@@ -92,7 +95,9 @@ export default class ComponentController extends BaseController {
     }
 
     findRoots = async (request: Request, response: Response) => {
-        const roots = await Component.findRoots(this.componentRepository, this.getMementoDate(request));
+        const mementoDate: Date | undefined = this.getMementoDate(request);
+        const roots = await Component.findRoots(this.componentRepository, mementoDate);
+        this.setMementoHeaderIfNecessary(mementoDate, response);
         if(roots) {
             const result: Record<string, unknown>[] = roots.map((root) => { return root.toJSONLD(); });
             this.setJSONLDResponseType(response);