diff --git a/core/src/main/java/org/elasticsearch/bootstrap/Bootstrap.java b/core/src/main/java/org/elasticsearch/bootstrap/Bootstrap.java
index ecd26673919..0d8ef345336 100644
--- a/core/src/main/java/org/elasticsearch/bootstrap/Bootstrap.java
+++ b/core/src/main/java/org/elasticsearch/bootstrap/Bootstrap.java
@@ -179,6 +179,9 @@ public class Bootstrap {
         // install any plugins into classpath
         setupPlugins(environment);
         
+        // look for jar hell
+        JarHell.checkJarHell();
+        
         // install SM after natives, shutdown hooks, etc.
         setupSecurity(settings, environment);
 
@@ -375,7 +378,8 @@ public class Bootstrap {
             return;
         }
 
-        ClassLoader classLoader = ClassLoader.getSystemClassLoader();
+        // note: there's only one classloader here, but Uwe gets upset otherwise.
+        ClassLoader classLoader = Bootstrap.class.getClassLoader();
         Class<?> classLoaderClass = classLoader.getClass();
         Method addURL = null;
         while (!classLoaderClass.equals(Object.class)) {
diff --git a/core/src/main/java/org/elasticsearch/bootstrap/JarHell.java b/core/src/main/java/org/elasticsearch/bootstrap/JarHell.java
new file mode 100644
index 00000000000..5ab6350e729
--- /dev/null
+++ b/core/src/main/java/org/elasticsearch/bootstrap/JarHell.java
@@ -0,0 +1,102 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.bootstrap;
+
+import org.elasticsearch.common.SuppressForbidden;
+import org.elasticsearch.common.io.PathUtils;
+
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+/** Simple check for duplicate class files across the classpath */
+class JarHell {
+
+    /**
+     * Checks the current classloader for duplicate classes
+     * @throws IllegalStateException if jar hell was found
+     */
+    @SuppressForbidden(reason = "needs JarFile for speed, just reading entries")
+    static void checkJarHell() throws Exception {
+        ClassLoader loader = JarHell.class.getClassLoader();
+        if (loader instanceof URLClassLoader == false) {
+           return;
+        }
+        final Map<String,URL> clazzes = new HashMap<>(32768);
+        Set<String> seenJars = new HashSet<>();
+        for (final URL url : ((URLClassLoader)loader).getURLs()) {
+            String path = url.getPath();
+            if (path.endsWith(".jar")) {
+                if (!seenJars.add(path)) {
+                    continue; // we can't fail because of sheistiness with joda-time
+                }
+                try (JarFile file = new JarFile(url.getPath())) {
+                    Enumeration<JarEntry> elements = file.entries();
+                    while (elements.hasMoreElements()) {
+                        String entry = elements.nextElement().getName();
+                        if (entry.endsWith(".class")) {
+                            checkClass(clazzes, entry, url);
+                        }
+                    }
+                }
+            } else {
+                Files.walkFileTree(PathUtils.get(url.toURI()), new SimpleFileVisitor<Path>() {
+                    @Override
+                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+                        String entry = file.toString();
+                        if (entry.endsWith(".class")) {
+                            checkClass(clazzes, entry, url);
+                        }
+                        return super.visitFile(file, attrs);
+                    }
+                });
+            }
+        }
+    }
+    
+    @SuppressForbidden(reason = "proper use of URL to reduce noise")
+    static void checkClass(Map<String,URL> clazzes, String clazz, URL url) {
+        if (clazz.startsWith("org/apache/log4j")) {
+            return; // go figure, jar hell for what should be System.out.println...
+        }
+        if (clazz.equals("org/joda/time/base/BaseDateTime.class")) {
+            return; // apparently this is intentional... clean this up
+        }
+        URL previous = clazzes.put(clazz, url);
+        if (previous != null) {
+            throw new IllegalStateException("jar hell!" + System.lineSeparator() +
+                    "class: " + clazz + System.lineSeparator() +
+                    "jar1: " + previous.getPath() + System.lineSeparator() +
+                    "jar2: " + url.getPath());
+        }
+    }
+}
diff --git a/core/src/main/java/org/elasticsearch/bootstrap/Security.java b/core/src/main/java/org/elasticsearch/bootstrap/Security.java
index 6bd000e37e4..3e4391aceac 100644
--- a/core/src/main/java/org/elasticsearch/bootstrap/Security.java
+++ b/core/src/main/java/org/elasticsearch/bootstrap/Security.java
@@ -81,7 +81,7 @@ final class Security {
      */
     @SuppressForbidden(reason = "proper use of URL")
     static void setCodebaseProperties() {
-        ClassLoader loader = ClassLoader.getSystemClassLoader();
+        ClassLoader loader = Security.class.getClassLoader();
         if (loader instanceof URLClassLoader) {
             for (URL url : ((URLClassLoader)loader).getURLs()) {
                 for (Map.Entry<Pattern,String> e : SPECIAL_JARS.entrySet()) {
diff --git a/core/src/test/java/org/elasticsearch/action/bulk/BulkProcessorTests.java b/core/src/test/java/org/elasticsearch/action/bulk/BulkProcessorTests.java
index ad1e9d97719..358ffb820f9 100644
--- a/core/src/test/java/org/elasticsearch/action/bulk/BulkProcessorTests.java
+++ b/core/src/test/java/org/elasticsearch/action/bulk/BulkProcessorTests.java
@@ -19,7 +19,7 @@
 
 package org.elasticsearch.action.bulk;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.carrotsearch.randomizedtesting.generators.RandomPicks;
+import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 
 import org.elasticsearch.action.get.MultiGetItemResponse;
 import org.elasticsearch.action.get.MultiGetRequestBuilder;
diff --git a/core/src/test/java/org/elasticsearch/bootstrap/BootstrapForTesting.java b/core/src/test/java/org/elasticsearch/bootstrap/BootstrapForTesting.java
index 56d6e42fd4d..1fbb1462ac6 100644
--- a/core/src/test/java/org/elasticsearch/bootstrap/BootstrapForTesting.java
+++ b/core/src/test/java/org/elasticsearch/bootstrap/BootstrapForTesting.java
@@ -50,6 +50,13 @@ public class BootstrapForTesting {
     static {
         // just like bootstrap, initialize natives, then SM
         Bootstrap.initializeNatives(true, true, true);
+        
+        // check for jar hell
+        try {
+            JarHell.checkJarHell();
+        } catch (Exception e) {
+            throw new RuntimeException("found jar hell in test classpath", e);
+        }
 
         // make sure java.io.tmpdir exists always (in case code uses it in a static initializer)
         Path javaTmpDir = PathUtils.get(Objects.requireNonNull(System.getProperty("java.io.tmpdir"),
diff --git a/core/src/test/java/org/elasticsearch/client/node/NodeClientHeadersTests.java b/core/src/test/java/org/elasticsearch/client/node/NodeClientHeadersTests.java
index be2df27197b..429cafdef54 100644
--- a/core/src/test/java/org/elasticsearch/client/node/NodeClientHeadersTests.java
+++ b/core/src/test/java/org/elasticsearch/client/node/NodeClientHeadersTests.java
@@ -19,10 +19,12 @@
 
 package org.elasticsearch.client.node;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSet;
+
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.ActionRequest;
 import org.elasticsearch.action.GenericAction;
+import org.elasticsearch.action.support.ActionFilter;
 import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.action.support.TransportAction;
 import org.elasticsearch.client.AbstractClientHeadersTests;
@@ -31,6 +33,7 @@ import org.elasticsearch.client.support.Headers;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.threadpool.ThreadPool;
 
+import java.util.Collections;
 import java.util.HashMap;
 
 /**
@@ -38,7 +41,7 @@ import java.util.HashMap;
  */
 public class NodeClientHeadersTests extends AbstractClientHeadersTests {
 
-    private static final ActionFilters EMPTY_FILTERS = new ActionFilters(ImmutableSet.of());
+    private static final ActionFilters EMPTY_FILTERS = new ActionFilters(Collections.<ActionFilter>emptySet());
 
     @Override
     protected Client buildClient(Settings headersSettings, GenericAction[] testedActions) {
diff --git a/core/src/test/java/org/elasticsearch/common/collect/CopyOnWriteHashMapTests.java b/core/src/test/java/org/elasticsearch/common/collect/CopyOnWriteHashMapTests.java
index f86f4cf8556..6cdde469418 100644
--- a/core/src/test/java/org/elasticsearch/common/collect/CopyOnWriteHashMapTests.java
+++ b/core/src/test/java/org/elasticsearch/common/collect/CopyOnWriteHashMapTests.java
@@ -19,7 +19,7 @@
 
 package org.elasticsearch.common.collect;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableMap;
 import org.elasticsearch.test.ElasticsearchTestCase;
 
 import java.util.HashMap;
diff --git a/core/src/test/java/org/elasticsearch/common/lucene/index/FreqTermsEnumTests.java b/core/src/test/java/org/elasticsearch/common/lucene/index/FreqTermsEnumTests.java
index 02468f98cee..840ebd8e9b8 100644
--- a/core/src/test/java/org/elasticsearch/common/lucene/index/FreqTermsEnumTests.java
+++ b/core/src/test/java/org/elasticsearch/common/lucene/index/FreqTermsEnumTests.java
@@ -19,8 +19,8 @@
 
 package org.elasticsearch.common.lucene.index;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.Lists;
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.Maps;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 
 import org.apache.lucene.analysis.core.KeywordAnalyzer;
diff --git a/core/src/test/java/org/elasticsearch/index/store/CorruptedFileTest.java b/core/src/test/java/org/elasticsearch/index/store/CorruptedFileTest.java
index f98a775dfe8..0ee11bdce53 100644
--- a/core/src/test/java/org/elasticsearch/index/store/CorruptedFileTest.java
+++ b/core/src/test/java/org/elasticsearch/index/store/CorruptedFileTest.java
@@ -18,10 +18,11 @@
  */
 package org.elasticsearch.index.store;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.Lists;
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 import com.google.common.base.Charsets;
 import com.google.common.base.Predicate;
+import com.google.common.collect.Lists;
+
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.index.CheckIndex;
 import org.apache.lucene.index.IndexFileNames;
diff --git a/core/src/test/java/org/elasticsearch/index/store/CorruptedTranslogTests.java b/core/src/test/java/org/elasticsearch/index/store/CorruptedTranslogTests.java
index b03c7d90327..ae37466981b 100644
--- a/core/src/test/java/org/elasticsearch/index/store/CorruptedTranslogTests.java
+++ b/core/src/test/java/org/elasticsearch/index/store/CorruptedTranslogTests.java
@@ -19,7 +19,7 @@
 
 package org.elasticsearch.index.store;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.Lists;
+import com.google.common.collect.Lists;
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 
 import org.elasticsearch.action.admin.cluster.node.stats.NodesStatsResponse;
diff --git a/core/src/test/java/org/elasticsearch/test/XContentTestUtils.java b/core/src/test/java/org/elasticsearch/test/XContentTestUtils.java
index 1f1b8eff710..917c66a452b 100644
--- a/core/src/test/java/org/elasticsearch/test/XContentTestUtils.java
+++ b/core/src/test/java/org/elasticsearch/test/XContentTestUtils.java
@@ -19,7 +19,7 @@
 
 package org.elasticsearch.test;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.Lists;
+import com.google.common.collect.Lists;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
diff --git a/core/src/test/java/org/elasticsearch/transport/ContextAndHeaderTransportTests.java b/core/src/test/java/org/elasticsearch/transport/ContextAndHeaderTransportTests.java
index db9219785c8..40cb626ce93 100644
--- a/core/src/test/java/org/elasticsearch/transport/ContextAndHeaderTransportTests.java
+++ b/core/src/test/java/org/elasticsearch/transport/ContextAndHeaderTransportTests.java
@@ -19,7 +19,6 @@
 
 package org.elasticsearch.transport;
 
-import com.carrotsearch.ant.tasks.junit4.dependencies.com.google.common.collect.ImmutableList;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClients;
 import org.elasticsearch.action.*;
@@ -380,7 +379,9 @@ public class ContextAndHeaderTransportTests extends ElasticsearchIntegrationTest
 
         @Override
         public Collection<Class<? extends Module>> modules() {
-            return ImmutableList.of(ActionLoggingModule.class);
+            Collection<Class<? extends Module>> classes = new ArrayList<>();
+            classes.add(ActionLoggingModule.class);
+            return classes;
         }
     }
 
diff --git a/plugins/pom.xml b/plugins/pom.xml
index 00706f9c088..b40ebb74fac 100644
--- a/plugins/pom.xml
+++ b/plugins/pom.xml
@@ -29,11 +29,6 @@
             <artifactId>hamcrest-all</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.apache.lucene</groupId>
             <artifactId>lucene-test-framework</artifactId>
diff --git a/pom.xml b/pom.xml
index 31262ac3a82..b637996bb0e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -163,6 +163,13 @@
                 <groupId>org.apache.lucene</groupId>
                 <artifactId>lucene-test-framework</artifactId>
                 <version>${lucene.maven.version}</version>
+                <!-- we specify our own junit4 version -->
+                <exclusions>
+                    <exclusion>
+                        <groupId>com.carrotsearch.randomizedtesting</groupId>
+                        <artifactId>junit4-ant</artifactId>
+                    </exclusion>
+                </exclusions>
             </dependency>
 
             <dependency>