diff --git a/ci/minecraft-server/test-values.yaml b/ci/minecraft-server/test-values.yaml
index 533e560..bb15dd7 100644
--- a/ci/minecraft-server/test-values.yaml
+++ b/ci/minecraft-server/test-values.yaml
@@ -7,9 +7,11 @@
 #    1.16.5, 1.18-1.20.4 need Java 17, and 1.20.5+ need Java 21. No single
 #    Minecraft version boots on all three lines, so this value is bumped
 #    together with appVersion in every Java-line PR.
-#    This chart version publishes appVersion "java17", hence 1.20.1.
-#    The production default is "LATEST", which would pull a 1.21.x server that
-#    needs Java 21 and would not start on this line.
+#    This chart version publishes appVersion "java21", hence 1.21.1 - which is
+#    also what ftb-skies-2, the one server actually running on this line, sets
+#    in its real values file, so CI exercises the production version rather
+#    than an arbitrary Java-21-capable one.
+#    The production default is "LATEST", which would drift on every restart.
 # 2. minecraft.resources.storage: the production 32Gi world volume is backed by
 #    a static hostPath PV in CI (see fixtures.yaml); 2Gi is plenty for a server
 #    that only has to boot.
@@ -25,7 +27,7 @@ secrets:
   minecraftServerRef: vaults/CI/items/minecraft-server
 
 minecraft:
-  version: "1.20.1"
+  version: "1.21.1"
   management:
     # opPlayers deliberately stays at the default (null): the image resolves
     # every name in OPS against the external Playerdb API and aborts the whole
diff --git a/minecraft-server/Chart.yaml b/minecraft-server/Chart.yaml
index 49a513c..9a8d9af 100644
--- a/minecraft-server/Chart.yaml
+++ b/minecraft-server/Chart.yaml
@@ -15,10 +15,10 @@ type: application
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
 # Versions are expected to follow Semantic Versioning (https://semver.org/)
-version: 0.4.0+upjava17
+version: 0.4.0+upjava21
 
 # This is the version number of the application being deployed. This version number should be
 # incremented each time you make changes to the application. Versions are not expected to
 # follow Semantic Versioning. They should reflect the version the application is using.
 # It is recommended to use it with quotes.
-appVersion: "java17"
+appVersion: "java21"