diff --git a/Dockerfile.azul b/Dockerfile.azul
index bb9aca4..597aa35 100644
--- a/Dockerfile.azul
+++ b/Dockerfile.azul
@@ -1,4 +1,4 @@
-FROM azul/zulu-openjdk:17-latest AS build
+FROM azul/zulu-openjdk:21-latest AS build
 
 WORKDIR /app/
 
@@ -7,7 +7,7 @@ COPY . /app/
 RUN --mount=type=cache,target=/root/.gradle/caches/ \
  ./gradlew shadowJar
 
-FROM azul/zulu-openjdk:17-jre-headless-latest
+FROM azul/zulu-openjdk:21-jre-headless-latest
 
 RUN --mount=type=cache,target=/var/cache/apt/ \
  apt-get update && \
diff --git a/Dockerfile.azul.ci b/Dockerfile.azul.ci
index 8c99e26..1cb27a2 100644
--- a/Dockerfile.azul.ci
+++ b/Dockerfile.azul.ci
@@ -1,4 +1,4 @@
-FROM azul/zulu-openjdk:17-jre-headless-latest
+FROM azul/zulu-openjdk:21-jre-headless-latest
 
 RUN --mount=type=cache,target=/var/cache/apt/ \
  apt-get update && \