diff --git a/Dockerfile b/Dockerfile
index 7236766..5731ced 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,6 +3,10 @@ FROM node:18-alpine
 LABEL maintainer="Frambe"
 LABEL description="Frambe — lightweight digital photo frame for Immich"
 
+# tzdata lets the TZ env var set the container's local time, which the
+# sleep scheduler relies on. Without it Alpine defaults to UTC.
+RUN apk add --no-cache tzdata
+
 WORKDIR /app
 
 COPY package.json ./