diff --git a/kotlin-dev/Dockerfile b/kotlin-dev/Dockerfile
index efdb6c6..8c0d04c 100644
--- a/kotlin-dev/Dockerfile
+++ b/kotlin-dev/Dockerfile
@@ -1,9 +1,9 @@
 FROM git.luke-else.co.uk/luke-else/lab:latest
 
-RUN apk add --no-cache unzip openjdk21
+RUN apk add --no-cache unzip zip openjdk21
 
 # Set Java environment variables
-ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk
+ENV JAVA_HOME=/usr/lib/jvm/java-21-openjdk
 ENV PATH="$JAVA_HOME/bin:$PATH"
 
 # Install SDKMAN and use it to install Kotlin and Gradle