diff --git a/Dockerfile b/Dockerfile
index be5f24a..2f79537 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,4 @@
-
-FROM alpine:3.19 AS build
+FROM alpine:3.21 AS build
 
 RUN apk add --no-cache gcc musl-dev
 
@@ -7,28 +6,21 @@ WORKDIR /app
 COPY . .
 RUN gcc -o deployment deployment.c
 
-# Final-Stage
-FROM alpine:3.19
-
+FROM alpine:3.21
 
 RUN adduser -D -u 1000 appuser
 
 WORKDIR /app
 
-
 RUN mkdir /output && chown appuser:appuser /output
 
-
 COPY --from=build /app/deployment .
 RUN chown appuser:appuser ./deployment
 
-# Volume deklarieren → Drone/Docker kann es mounten
 VOLUME ["/output"]
 
-# Als non-root laufen
 USER appuser
 
-# Healthcheck: prüft ob Output geschrieben wurde
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
   CMD test -f /output/output.txt || exit 1