diff --git a/demo/Dockerfile b/demo/Dockerfile
index 4096cb51f..af5f3c778 100644
--- a/demo/Dockerfile
+++ b/demo/Dockerfile
@@ -23,7 +23,7 @@ RUN CGO_ENABLED=0 make -C /src VERSION="${VERSION:-dev}" karma
 
 FROM alpine:3.12
 COPY --from=lmierzwa/kthxbye:v0.7 /kthxbye /kthxbye
-COPY --from=prom/alertmanager:v0.20.0 /bin/alertmanager /alertmanager
+COPY --from=prom/alertmanager:v0.21.0 /bin/alertmanager /alertmanager
 RUN apk add supervisor python3 && rm  -rf /tmp/* /var/cache/apk/*
 COPY demo/supervisord.conf /etc/supervisord.conf
 COPY demo/alertmanager.yaml /etc/alertmanager.yaml