diff --git a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
index 628e59de1a6..798f1d230ae 100644
--- a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
+++ b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
@@ -509,11 +509,9 @@ class BuildPlugin implements Plugin<Project> {
                 }
             }
 
-            // System assertions (-esa) are disabled for now because of what looks like a
-            // JDK bug triggered by Groovy on JDK7. We should look at re-enabling system
-            // assertions when we upgrade to a new version of Groovy (currently 2.4.4) or
-            // require JDK8. See https://issues.apache.org/jira/browse/GROOVY-7528.
-            enableSystemAssertions false
+            boolean assertionsEnabled = Boolean.parseBoolean(System.getProperty('tests.asserts', 'true'))
+            enableSystemAssertions assertionsEnabled
+            enableAssertions assertionsEnabled
 
             testLogging {
                 showNumFailuresAtEnd 25
diff --git a/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy b/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy
index 57adaa2576d..8d65f8c0d60 100644
--- a/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy
+++ b/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy
@@ -72,12 +72,10 @@ class ClusterConfiguration {
     boolean useMinimumMasterNodes = true
 
     @Input
-    String jvmArgs = "-ea" +
-        " " + "-Xms" + System.getProperty('tests.heap.size', '512m') +
+    String jvmArgs = "-Xms" + System.getProperty('tests.heap.size', '512m') +
         " " + "-Xmx" + System.getProperty('tests.heap.size', '512m') +
         " " + System.getProperty('tests.jvm.argline', '')
 
-
     /**
      * A closure to call which returns the unicast host to connect to for cluster formation.
      *
diff --git a/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy b/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy
index a9473cc28d2..73f32961fb3 100644
--- a/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy
+++ b/buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy
@@ -151,6 +151,9 @@ class NodeInfo {
         args.addAll("-E", "node.portsfile=true")
         String collectedSystemProperties = config.systemProperties.collect { key, value -> "-D${key}=${value}" }.join(" ")
         String esJavaOpts = config.jvmArgs.isEmpty() ? collectedSystemProperties : collectedSystemProperties + " " + config.jvmArgs
+        if (Boolean.parseBoolean(System.getProperty('tests.asserts', 'true'))) {
+            esJavaOpts += " -ea -esa"
+        }
         env.put('ES_JAVA_OPTS', esJavaOpts)
         for (Map.Entry<String, String> property : System.properties.entrySet()) {
             if (property.key.startsWith('tests.es.')) {