diff --git a/pom.xml b/pom.xml
index 19ddf997057..8a757e67d37 100644
--- a/pom.xml
+++ b/pom.xml
@@ -427,6 +427,7 @@
                                 <tests.integration>${tests.integration}</tests.integration>
                                 <tests.cluster_seed>${tests.cluster_seed}</tests.cluster_seed>
                                 <tests.client.ratio>${tests.client.ratio}</tests.client.ratio>
+                                <tests.enable_mock_modules>${tests.enable_mock_modules}</tests.enable_mock_modules>
                                 <tests.rest>${tests.rest}</tests.rest>
                                 <tests.rest.suite>${tests.rest.suite}</tests.rest.suite>
                                 <tests.rest.spec>${tests.rest.spec}</tests.rest.spec>
diff --git a/src/test/java/org/elasticsearch/test/ElasticsearchIntegrationTest.java b/src/test/java/org/elasticsearch/test/ElasticsearchIntegrationTest.java
index 7e573404a07..f2bb75dff79 100644
--- a/src/test/java/org/elasticsearch/test/ElasticsearchIntegrationTest.java
+++ b/src/test/java/org/elasticsearch/test/ElasticsearchIntegrationTest.java
@@ -125,6 +125,8 @@ import static org.hamcrest.Matchers.equalTo;
  *   <ul>
  *   <li>-D{@value #TESTS_CLIENT_RATIO} - a double value in the interval [0..1] which defines the ration between node and transport clients used</li>
  *   <li>-D{@value TestCluster#TESTS_CLUSTER_SEED} - a random seed used to initialize the clusters random context.
+ *   <li>-D{@value TestCluster#TESTS_ENABLE_MOCK_MODULES} - a boolean value to enable or disable mock modules. This is
+ *   useful to test the system without asserting modules that to make sure they don't hide any bugs in production.</li>
  *   <li>-D{@value #INDEX_SEED_SETTING} - a random seed used to initialize the index random context.
  *   </ul>
  * </p>
diff --git a/src/test/java/org/elasticsearch/test/TestCluster.java b/src/test/java/org/elasticsearch/test/TestCluster.java
index 8a9248b52b5..15092378d4d 100644
--- a/src/test/java/org/elasticsearch/test/TestCluster.java
+++ b/src/test/java/org/elasticsearch/test/TestCluster.java
@@ -62,7 +62,10 @@ import java.util.*;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import static com.carrotsearch.randomizedtesting.RandomizedTest.systemPropertyAsBoolean;
 import static com.google.common.collect.Maps.newTreeMap;
+import static org.apache.lucene.util.LuceneTestCase.rarely;
+import static org.apache.lucene.util.LuceneTestCase.usually;
 import static org.elasticsearch.common.settings.ImmutableSettings.settingsBuilder;
 import static org.elasticsearch.node.NodeBuilder.nodeBuilder;
 
@@ -91,6 +94,13 @@ public final class TestCluster implements Iterable<Client> {
      */
     public static final String TESTS_CLUSTER_SEED = "tests.cluster_seed";
 
+    /**
+     * Key used to set the shared cluster random seed via the commandline -D{@value #TESTS_CLUSTER_SEED}
+     */
+    public static final String TESTS_ENABLE_MOCK_MODULES = "tests.enable_mock_modules";
+
+    private static final boolean ENABLE_MOCK_MODULES = systemPropertyAsBoolean(TESTS_ENABLE_MOCK_MODULES, true);
+
     private static long clusterSeed() {
         String property = System.getProperty(TESTS_CLUSTER_SEED);
         if (!Strings.hasLength(property)) {
@@ -191,18 +201,19 @@ public final class TestCluster implements Iterable<Client> {
         Builder builder = ImmutableSettings.settingsBuilder()
         /* use RAM directories in 10% of the runs */
         //.put("index.store.type", random.nextInt(10) == 0 ? MockRamIndexStoreModule.class.getName() : MockFSIndexStoreModule.class.getName())
-                // TODO we should run without those mock modules once in a while to make sure we don't hide any bugs in the actual impl.
-                .put("index.store.type", MockFSIndexStoreModule.class.getName()) // no RAM dir for now!
-                .put(IndexEngineModule.EngineSettings.ENGINE_TYPE, MockEngineModule.class.getName())
                 .put("cluster.name", clusterName)
                         // decrease the routing schedule so new nodes will be added quickly - some random value between 30 and 80 ms
                 .put("cluster.routing.schedule", (30 + random.nextInt(50)) + "ms")
                         // default to non gateway
                 .put("gateway.type", "none");
+        if (ENABLE_MOCK_MODULES && usually(random)) {
+            builder.put("index.store.type", MockFSIndexStoreModule.class.getName()); // no RAM dir for now!
+            builder.put(IndexEngineModule.EngineSettings.ENGINE_TYPE, MockEngineModule.class.getName());
+        }
         if (isLocalTransportConfigured()) {
             builder.put(TransportModule.TRANSPORT_TYPE_KEY, AssertingLocalTransportModule.class.getName());
         } else {
-            builder.put(Transport.TransportSettings.TRANSPORT_TCP_COMPRESS, random.nextInt(10) == 0);
+            builder.put(Transport.TransportSettings.TRANSPORT_TCP_COMPRESS, rarely(random));
         }
         builder.put("type", RandomPicks.randomFrom(random, CacheRecycler.Type.values()));
         return builder.build();
diff --git a/src/test/java/org/elasticsearch/test/junit/listeners/ReproduceInfoPrinter.java b/src/test/java/org/elasticsearch/test/junit/listeners/ReproduceInfoPrinter.java
index 56f2c231fc2..daefbfab208 100644
--- a/src/test/java/org/elasticsearch/test/junit/listeners/ReproduceInfoPrinter.java
+++ b/src/test/java/org/elasticsearch/test/junit/listeners/ReproduceInfoPrinter.java
@@ -9,6 +9,7 @@ import org.elasticsearch.common.logging.ESLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
 import org.elasticsearch.test.ElasticsearchTestCase;
+import org.elasticsearch.test.TestCluster;
 import org.junit.internal.AssumptionViolatedException;
 import org.junit.runner.Description;
 import org.junit.runner.notification.Failure;
@@ -111,7 +112,7 @@ public class ReproduceInfoPrinter extends RunListener {
         }
 
         public ReproduceErrorMessageBuilder appendESProperties() {
-            appendProperties("es.logger.level", "es.node.mode", "es.node.local");
+            appendProperties("es.logger.level", "es.node.mode", "es.node.local", TestCluster.TESTS_ENABLE_MOCK_MODULES);
 
             if (System.getProperty("tests.jvm.argline") != null && !System.getProperty("tests.jvm.argline").isEmpty()) {
                 appendOpt("tests.jvm.argline", "\"" + System.getProperty("tests.jvm.argline") + "\"");