diff --git a/src/logic/last-modified-middleware.ts b/src/logic/last-modified-middleware.ts
index 51a4cb7..39cb068 100644
--- a/src/logic/last-modified-middleware.ts
+++ b/src/logic/last-modified-middleware.ts
@@ -14,28 +14,31 @@ export function lastModifiedMiddleware(
   const cacheControlHeader = `max-age=${options.maxAge}, stale-while-revalidate=${options.staleWhileRevalidate}, public`
 
   return async (context, next): Promise<IHttpServerComponent.IResponse> => {
-    // const lastModifiedTime = getLastModifiedTime()
-    // const ifModifiedSinceHeader =
-    //   context.request.headers.get('If-Modified-Since')
+    const lastModifiedTime = getLastModifiedTime()
+    const lastModifiedHeader = new Date(lastModifiedTime).toUTCString()
+    const ifModifiedSinceHeader =
+      context.request.headers.get('If-Modified-Since')
 
-    // if (ifModifiedSinceHeader) {
-    //   const ifModifiedSinceTime = Date.parse(ifModifiedSinceHeader)
-    //   if (
-    //     !isNaN(ifModifiedSinceTime) &&
-    //     lastModifiedTime <= ifModifiedSinceTime
-    //   ) {
-    //     return {
-    //       status: 304,
-    //       headers: {
-    //         'Cache-Control': cacheControlHeader,
-    //       },
-    //     }
-    //   }
-    // }
+    if (ifModifiedSinceHeader) {
+      const ifModifiedSinceTime = Date.parse(ifModifiedSinceHeader)
+      if (
+        !isNaN(ifModifiedSinceTime) &&
+        lastModifiedTime <= ifModifiedSinceTime
+      ) {
+        return {
+          status: 304,
+          headers: {
+            'Last-Modified': lastModifiedHeader,
+            'Cache-Control': cacheControlHeader,
+          },
+        }
+      }
+    }
 
     const response = await next()
     response.headers = {
       ...response.headers,
+      'Last-Modified': lastModifiedHeader,
       'Cache-Control': cacheControlHeader,
     }
 
diff --git a/tests/logic/last-modified-middlware-logic.spec.ts b/tests/logic/last-modified-middlware-logic.spec.ts
index 1b53ec6..0221f59 100644
--- a/tests/logic/last-modified-middlware-logic.spec.ts
+++ b/tests/logic/last-modified-middlware-logic.spec.ts
@@ -23,7 +23,7 @@ beforeEach(() => {
   middleware = lastModifiedMiddleware(mockedGetLastModifiedTime)
 })
 
-describe.skip('when handling a request with a If-Modified-Since header', () => {
+describe('when handling a request with a If-Modified-Since header', () => {
   describe('when the If-Modified-Since header is a valid date', () => {
     beforeEach(() => {
       mockedRequest.headers.set(
@@ -50,7 +50,7 @@ describe.skip('when handling a request with a If-Modified-Since header', () => {
       })
     })
 
-    describe.skip('when the If-Modified-Since header is the same as last modified time', () => {
+    describe('when the If-Modified-Since header is the same as last modified time', () => {
       beforeEach(() => {
         lastModifiedUTSCString = 'Tue, 20 Jan 1970 11:55:03 GMT'
         mockedResponse = { status: 200, body: 'ok' }
@@ -110,7 +110,7 @@ describe.skip('when handling a request with a If-Modified-Since header', () => {
   })
 })
 
-describe.skip('when handling a request without a If-Modified-Since header', () => {
+describe('when handling a request without a If-Modified-Since header', () => {
   beforeEach(() => {
     lastModifiedUTSCString = 'Sun, 25 Jan 1970 10:00:03 GMT'
     mockedResponse = { status: 200, body: 'ok' }
@@ -129,7 +129,7 @@ describe.skip('when handling a request without a If-Modified-Since header', () =
   })
 })
 
-describe.skip('when setting the max age and the stale while revalidate options', () => {
+describe('when setting the max age and the stale while revalidate options', () => {
   beforeEach(() => {
     lastModifiedUTSCString = 'Sun, 25 Jan 1970 10:00:03 GMT'
     mockedResponse = { status: 200, body: 'ok' }
diff --git a/tests/modules/api.spec.ts b/tests/modules/api.spec.ts
index 70262be..7c7cc79 100644
--- a/tests/modules/api.spec.ts
+++ b/tests/modules/api.spec.ts
@@ -320,7 +320,7 @@ beforeEach(async () => {
 })
 
 describe('when fetching data', () => {
-  describe('and fetching the graph fails but the rental listings', () => {
+  describe('and fetching the graph fails', () => {
     beforeEach(() => {
       subgraphComponentMock.query = jest
         .fn()
@@ -394,8 +394,10 @@ describe('when fetching data', () => {
     let sixthParcelEstate: ParcelFragment
     let fourthParcelRentalListing: RentalListing
     let fifthParcelEstateRentalListing: RentalListing
+    let maxDateInSeconds: number
 
     beforeEach(() => {
+      maxDateInSeconds = fromMillisecondsToSeconds(date) + 5
       fourthParcel = {
         ...defaultParcel,
         id: 'parcel-0x0-3',
@@ -405,6 +407,7 @@ describe('when fetching data', () => {
         searchParcelEstateId: null,
         tokenId: '3',
         activeOrder: null,
+        updatedAt: maxDateInSeconds.toString(),
         parcel: {
           ...defaultParcel.parcel,
           data: {
@@ -422,6 +425,7 @@ describe('when fetching data', () => {
         searchParcelY: '3',
         searchParcelEstateId: 'estate-0x0-2',
         tokenId: '4',
+        updatedAt: (maxDateInSeconds - 1).toString(),
         parcel: {
           data: {
             name: 'Parcel 4',
@@ -452,6 +456,7 @@ describe('when fetching data', () => {
         name: 'Parcel 5',
         searchParcelX: '5',
         searchParcelY: '3',
+        updatedAt: (maxDateInSeconds - 2).toString(),
         parcel: {
           ...fifthParcelEstate.parcel,
           data: {
@@ -764,7 +769,7 @@ describe('when fetching data', () => {
             background_color: '000000',
           },
         ],
-        updatedAt: Number(defaultParcel.updatedAt),
+        updatedAt: maxDateInSeconds,
       })
     })
   })
@@ -772,12 +777,20 @@ describe('when fetching data', () => {
 
 describe('when fetching update data', () => {
   let fstEstate: EstateFragment
+  let fstParcel: ParcelFragment
+  let fstParcelTile: Tile
   let defaultParcelRentalListing: RentalListing
   let fstEstateRentalListing: RentalListing
+  let maxDateInSeconds: number
 
   beforeEach(() => {
+    maxDateInSeconds = fromMillisecondsToSeconds(date)
+    fstParcel = {
+      ...defaultParcel,
+      updatedAt: (maxDateInSeconds - 1).toString()
+    }
     fstEstate = {
-      updatedAt: fromMillisecondsToSeconds(date).toString(),
+      updatedAt: maxDateInSeconds.toString(),
       estate: {
         parcels: [
           { nft: defaultFstParcelEstate },
@@ -785,6 +798,10 @@ describe('when fetching update data', () => {
         ],
       },
     }
+    fstParcelTile = {
+      ...defaultParcelTile,
+      updatedAt: maxDateInSeconds - 1
+    }
     defaultParcelRentalListing = {
       id: 'defaultParcelRentalId',
       status: RentalStatus.OPEN,
@@ -975,7 +992,7 @@ describe('when fetching update data', () => {
   describe('and there are parcels and estates to be updated', () => {
     beforeEach(() => {
       subgraphComponentMock.query = jest.fn().mockResolvedValueOnce({
-        parcels: [defaultParcel],
+        parcels: [fstParcel],
         estates: [fstEstate],
       })
       rentalsComponentMock.getUpdatedRentalListings = jest
@@ -987,7 +1004,7 @@ describe('when fetching update data', () => {
       return expect(apiComponent.fetchUpdatedData(100000, {})).resolves.toEqual(
         {
           tiles: [
-            defaultParcelTile,
+            fstParcelTile,
             defaultFstParcelEstateTile,
             defaultSndParcelEstateTile,
           ],
@@ -997,7 +1014,7 @@ describe('when fetching update data', () => {
             defaultSndParcelEstateNFT,
           ],
           estates: [fstEstateNFT],
-          updatedAt: Number(fstEstate.updatedAt),
+          updatedAt: maxDateInSeconds,
         }
       )
     })