diff --git a/config.py b/config.py
index 5e666a9..ce3bda5 100644
--- a/config.py
+++ b/config.py
@@ -1,3 +1,4 @@
 imgdir = "."
 refresh = 5
-cachedir = ".webslider"
+cachedir = "/tmp/webslider"
+resolution = (1920, 1080)
diff --git a/requirements.txt b/requirements.txt
index f1a6954..533b660 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
 Flask==1.0.2
 Pillow==5.3.0
+Click==7.0
diff --git a/slider.py b/slider.py
index da7d743..382e270 100755
--- a/slider.py
+++ b/slider.py
@@ -13,7 +13,8 @@ import config
 
 app = Flask(__name__)
 
-cache_resolution = (1920, 1080)
+imgdir = Path(config.imgdir).expanduser().resolve()
+cache_resolution = config.resolution
 cache_dir = Path(config.cachedir) / ("%sx%s" % cache_resolution)
 
 
@@ -25,7 +26,6 @@ def random():
 @app.route("/random_image/")
 def random_image():
     img_glob = "*jpg"
-    imgdir = Path(config.imgdir)
     last_modified_time, last_modified_file = max(
         (f.stat().st_mtime, f) for f in imgdir.glob(img_glob)
     )
@@ -36,7 +36,7 @@ def random_image():
         images = list(imgdir.glob(img_glob))
         selected_image = choice(images).relative_to(imgdir)
 
-    return redirect(url_for("image", filename=selected_image))
+    return redirect(url_for("image", filename=selected_image) + "?hash=%s" % get_cache_filename(selected_image))
 
 
 @app.route("/img/<path:filename>")
@@ -64,7 +64,7 @@ def create_cache_file(filename):
 
     if not (cache_dir / cache_file).exists():
         print("Creating cache file", filename)
-        img = Image.open(Path(config.imgdir) / filename)
+        img = Image.open(imgdir / filename)
         img.thumbnail(cache_resolution)
         img.save(cache_dir / cache_file, "JPEG")
 
@@ -72,12 +72,11 @@ def create_cache_file(filename):
 
 
 def get_cache_filename(filename):
-    original_file_path = Path(config.imgdir) / filename
+    original_file_path = imgdir / filename
     return sha256(str(original_file_path.resolve()).encode("utf-8")).hexdigest()
 
 
 def pre_cache_images():
-    imgdir = Path(config.imgdir)
     for image_file in sorted(imgdir.glob("*.jpg")):
         create_cache_file(image_file.relative_to(imgdir))