diff --git a/internal/api/routes_gallery.go b/internal/api/routes_gallery.go
index e08663a70..585d46d4a 100644
--- a/internal/api/routes_gallery.go
+++ b/internal/api/routes_gallery.go
@@ -78,7 +78,7 @@ func (rs galleryRoutes) Cover(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	rs.imageRoutes.serveThumbnail(w, r, i)
+	rs.imageRoutes.serveThumbnail(w, r, i, &g.UpdatedAt)
 }
 
 func (rs galleryRoutes) Preview(w http.ResponseWriter, r *http.Request) {
@@ -116,7 +116,7 @@ func (rs galleryRoutes) Preview(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	rs.imageRoutes.serveThumbnail(w, r, i)
+	rs.imageRoutes.serveThumbnail(w, r, i, nil)
 }
 
 func (rs galleryRoutes) GalleryCtx(next http.Handler) http.Handler {
diff --git a/internal/api/routes_image.go b/internal/api/routes_image.go
index 89e6d2db4..598a6fe26 100644
--- a/internal/api/routes_image.go
+++ b/internal/api/routes_image.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"os/exec"
 	"strconv"
+	"time"
 
 	"github.com/go-chi/chi/v5"
 
@@ -47,17 +48,21 @@ func (rs imageRoutes) Routes() chi.Router {
 
 func (rs imageRoutes) Thumbnail(w http.ResponseWriter, r *http.Request) {
 	img := r.Context().Value(imageKey).(*models.Image)
-	rs.serveThumbnail(w, r, img)
+	rs.serveThumbnail(w, r, img, nil)
 }
 
-func (rs imageRoutes) serveThumbnail(w http.ResponseWriter, r *http.Request, img *models.Image) {
+func (rs imageRoutes) serveThumbnail(w http.ResponseWriter, r *http.Request, img *models.Image, modTime *time.Time) {
 	mgr := manager.GetInstance()
 	filepath := mgr.Paths.Generated.GetThumbnailPath(img.Checksum, models.DefaultGthumbWidth)
 
 	// if the thumbnail doesn't exist, encode on the fly
 	exists, _ := fsutil.FileExists(filepath)
 	if exists {
-		utils.ServeStaticFile(w, r, filepath)
+		if modTime == nil {
+			utils.ServeStaticFile(w, r, filepath)
+		} else {
+			utils.ServeStaticFileModTime(w, r, filepath, *modTime)
+		}
 	} else {
 		const useDefault = true
 
diff --git a/pkg/utils/http.go b/pkg/utils/http.go
index d2b40af99..a893a93f3 100644
--- a/pkg/utils/http.go
+++ b/pkg/utils/http.go
@@ -2,7 +2,10 @@ package utils
 
 import (
 	"bytes"
+	"errors"
+	"io/fs"
 	"net/http"
+	"path/filepath"
 	"time"
 
 	"github.com/stashapp/stash/pkg/hash/md5"
@@ -15,14 +18,18 @@ func GenerateETag(data []byte) string {
 	return `"` + hash + `"`
 }
 
-// Serves static content, adding Cache-Control: no-cache and a generated ETag header.
-// Responds to conditional requests using the ETag.
-func ServeStaticContent(w http.ResponseWriter, r *http.Request, data []byte) {
+func setStaticContentCacheControl(w http.ResponseWriter, r *http.Request) {
 	if r.URL.Query().Has("t") {
 		w.Header().Set("Cache-Control", "private, max-age=31536000, immutable")
 	} else {
 		w.Header().Set("Cache-Control", "no-cache")
 	}
+}
+
+// Serves static content, adding Cache-Control: no-cache and a generated ETag header.
+// Responds to conditional requests using the ETag.
+func ServeStaticContent(w http.ResponseWriter, r *http.Request, data []byte) {
+	setStaticContentCacheControl(w, r)
 	w.Header().Set("ETag", GenerateETag(data))
 
 	http.ServeContent(w, r, "", time.Time{}, bytes.NewReader(data))
@@ -31,11 +38,42 @@ func ServeStaticContent(w http.ResponseWriter, r *http.Request, data []byte) {
 // Serves static content at filepath, adding Cache-Control: no-cache.
 // Responds to conditional requests using the file modtime.
 func ServeStaticFile(w http.ResponseWriter, r *http.Request, filepath string) {
-	if r.URL.Query().Has("t") {
-		w.Header().Set("Cache-Control", "private, max-age=31536000, immutable")
-	} else {
-		w.Header().Set("Cache-Control", "no-cache")
-	}
+	setStaticContentCacheControl(w, r)
 
 	http.ServeFile(w, r, filepath)
 }
+
+func toHTTPError(err error) (msg string, httpStatus int) {
+	if errors.Is(err, fs.ErrNotExist) {
+		return "404 page not found", http.StatusNotFound
+	}
+	if errors.Is(err, fs.ErrPermission) {
+		return "403 Forbidden", http.StatusForbidden
+	}
+	return "500 Internal Server Error", http.StatusInternalServerError
+}
+
+// ServeStaticFileModTime serves a static file at the given path using the given modTime instead of the file modTime.
+func ServeStaticFileModTime(w http.ResponseWriter, r *http.Request, path string, modTime time.Time) {
+	setStaticContentCacheControl(w, r)
+
+	dir, file := filepath.Split(path)
+	fs := http.Dir(dir)
+
+	f, err := fs.Open(file)
+	if err != nil {
+		msg, code := toHTTPError(err)
+		http.Error(w, msg, code)
+		return
+	}
+	defer f.Close()
+
+	d, err := f.Stat()
+	if err != nil {
+		msg, code := toHTTPError(err)
+		http.Error(w, msg, code)
+		return
+	}
+
+	http.ServeContent(w, r, d.Name(), modTime, f)
+}