diff --git a/backend/middlewares/GalleryMWs.ts b/backend/middlewares/GalleryMWs.ts
index 1edac34a..80f5fe39 100644
--- a/backend/middlewares/GalleryMWs.ts
+++ b/backend/middlewares/GalleryMWs.ts
@@ -14,6 +14,7 @@ import {RandomQuery} from '../model/interfaces/IGalleryManager';
 import {MediaDTO} from '../../common/entities/MediaDTO';
 import {VideoDTO} from '../../common/entities/VideoDTO';
 import {Utils} from '../../common/Utils';
+import {QueryParams} from '../../common/QueryParams';
 
 
 const LOG_TAG = '[GalleryMWs]';
@@ -32,7 +33,9 @@ export class GalleryMWs {
 
     try {
       const directory = await ObjectManagerRepository.getInstance()
-        .GalleryManager.listDirectory(directoryName, req.query.knownLastModified, req.query.knownLastScanned);
+        .GalleryManager.listDirectory(directoryName,
+          parseInt(req.query[QueryParams.gallery.knownLastModified], 10),
+          parseInt(req.query[QueryParams.gallery.knownLastScanned], 10));
 
       if (directory == null) {
         req.resultPipe = new ContentWrapper(null, null, true);
diff --git a/backend/model/sql/GalleryManager.ts b/backend/model/sql/GalleryManager.ts
index f2a68405..a5021e53 100644
--- a/backend/model/sql/GalleryManager.ts
+++ b/backend/model/sql/GalleryManager.ts
@@ -94,11 +94,10 @@ export class GalleryManager implements IGalleryManager, ISQLGalleryManager {
       if (knownLastModified && knownLastScanned
         && lastModified === knownLastModified &&
         dir.lastScanned === knownLastScanned) {
-
         if (Config.Server.indexing.reIndexingSensitivity === ReIndexingSensitivity.low) {
           return null;
         }
-        if (Date.now() - knownLastScanned <= Config.Server.indexing.cachedFolderTimeout &&
+        if (Date.now() - dir.lastScanned <= Config.Server.indexing.cachedFolderTimeout &&
           Config.Server.indexing.reIndexingSensitivity === ReIndexingSensitivity.medium) {
           return null;
         }
@@ -349,9 +348,9 @@ export class GalleryManager implements IGalleryManager, ISQLGalleryManager {
       }
       await fileRepository.save(metaFilesToSave);
       await fileRepository.remove(indexedMetaFiles);
-    }catch (e){
+    } catch (e) {
       throw e;
-    }finally {
+    } finally {
       this.isSaving = false;
     }
   }
diff --git a/common/QueryParams.ts b/common/QueryParams.ts
index 1939eb3e..40327348 100644
--- a/common/QueryParams.ts
+++ b/common/QueryParams.ts
@@ -11,6 +11,8 @@ export const QueryParams = {
     },
     photo: 'p',
     sharingKey_short: 'sk',
-    sharingKey_long: 'sharingKey'
+    sharingKey_long: 'sharingKey',
+    knownLastModified: 'knownLastModified',
+    knownLastScanned: 'knownLastScanned'
   }
 };
diff --git a/frontend/app/gallery/gallery.service.ts b/frontend/app/gallery/gallery.service.ts
index f607174b..36d1a10b 100644
--- a/frontend/app/gallery/gallery.service.ts
+++ b/frontend/app/gallery/gallery.service.ts
@@ -66,8 +66,8 @@ export class GalleryService {
 
     if (content.directory && content.directory.lastModified && content.directory.lastScanned &&
       !content.directory.isPartial) {
-      params['knownLastModified'] = content.directory.lastModified;
-      params['knownLastScanned'] = content.directory.lastScanned;
+      params[QueryParams.gallery.knownLastModified] = content.directory.lastModified;
+      params[QueryParams.gallery.knownLastScanned] = content.directory.lastScanned;
     }
 
     try {
diff --git a/frontend/app/model/query.service.ts b/frontend/app/model/query.service.ts
index ee806781..0be440d9 100644
--- a/frontend/app/model/query.service.ts
+++ b/frontend/app/model/query.service.ts
@@ -46,8 +46,8 @@ export class QueryService {
     }
     if (directory && directory.lastModified && directory.lastScanned &&
       !directory.isPartial) {
-      params['knownLastModified'] = directory.lastModified;
-      params['knownLastScanned'] = directory.lastScanned;
+      params[QueryParams.gallery.knownLastModified] = directory.lastModified;
+      params[QueryParams.gallery.knownLastScanned] = directory.lastScanned;
     }
 
     return params;