diff --git a/Dockerfile b/Dockerfile
index 16068d1..1b2c34a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.19@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b as builder
+FROM alpine:3.21@sha256:b97e2a89d0b9e4011bb88c02ddf01c544b8c781acf1f4d559e7c8f12f1047ac3 as builder
 
 # renovate: datasource=github-tags depName=zerotier/ZeroTierOne tag=1.12.2
 ENV ZEROTIER_COMMIT=327eb9013b39809835a912c9117a0b9669f4661f
@@ -12,7 +12,7 @@ RUN set -eux; \
     make ZT_SSO_SUPPORTED=0; \
     DESTDIR=/tmp/build make install
 
-FROM alpine:3.19@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b
+FROM alpine:3.21@sha256:b97e2a89d0b9e4011bb88c02ddf01c544b8c781acf1f4d559e7c8f12f1047ac3
 
 COPY --from=builder /tmp/build/usr/sbin/* /usr/sbin/