diff --git a/src/test/java/uk/ac/cam/cl/dtg/isaac/api/IsaacIntegrationTest.java b/src/test/java/uk/ac/cam/cl/dtg/isaac/api/IsaacIntegrationTest.java
index e96b55b9eb..e5341ecbe2 100644
--- a/src/test/java/uk/ac/cam/cl/dtg/isaac/api/IsaacIntegrationTest.java
+++ b/src/test/java/uk/ac/cam/cl/dtg/isaac/api/IsaacIntegrationTest.java
@@ -211,6 +211,7 @@ public static void setUpClass() {
         .withEnv("xpack.security.enabled", "true")
         .withEnv("ELASTIC_PASSWORD", "elastic")
         .withEnv("ingest.geoip.downloader.enabled", "false")
+        .withEnv("ES_JAVA_OPTS", "-Xms512m -Xmx512m -Des.cgroup.v2.enabled=true")
         .withStartupTimeout(Duration.ofSeconds(120));
 
     postgres.start();
diff --git a/src/test/resources/isaac-test-es-docker-entrypoint.sh b/src/test/resources/isaac-test-es-docker-entrypoint.sh
index 1df4635800..2db810ca70 100755
--- a/src/test/resources/isaac-test-es-docker-entrypoint.sh
+++ b/src/test/resources/isaac-test-es-docker-entrypoint.sh
@@ -95,4 +95,9 @@ if [[ "$(id -u)" == "0" ]]; then
   fi
 fi
 
+
+# Ensure ES_JAVA_OPTS is available (fixes cgroup v2 startup on modern Linux/Docker)
+export ES_JAVA_OPTS="${ES_JAVA_OPTS:--Xms512m -Xmx512m -Des.cgroup.v2.enabled=true}"
+
+
 run_as_other_user_if_needed /usr/share/elasticsearch/bin/elasticsearch <<<"$KEYSTORE_PASSWORD"