diff --git a/server/src/main/java/io/druid/initialization/Initialization.java b/server/src/main/java/io/druid/initialization/Initialization.java
index 0752036575e..02825425aa1 100644
--- a/server/src/main/java/io/druid/initialization/Initialization.java
+++ b/server/src/main/java/io/druid/initialization/Initialization.java
@@ -78,13 +78,15 @@ import java.util.List;
 import java.util.Map;
 import java.util.ServiceLoader;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 /**
  */
 public class Initialization
 {
   private static final Logger log = new Logger(Initialization.class);
-  private static final Map<String, URLClassLoader> loadersMap = Maps.newHashMap();
+  private static final ConcurrentMap<File, URLClassLoader> loadersMap = new ConcurrentHashMap<>();
 
   private final static Map<Class, Set> extensionsMap = Maps.<Class, Set>newHashMap();
 
@@ -114,7 +116,7 @@ public class Initialization
   /**
    * Used for testing only
    */
-  static Map<String, URLClassLoader> getLoadersMap()
+  static Map<File, URLClassLoader> getLoadersMap()
   {
     return loadersMap;
   }
@@ -274,8 +276,8 @@ public class Initialization
         log.info("added URL[%s]", url);
         urls[i++] = url;
       }
-      loader = new URLClassLoader(urls, Initialization.class.getClassLoader());
-      loadersMap.put(extension.getName(), loader);
+      loadersMap.putIfAbsent(extension, new URLClassLoader(urls, Initialization.class.getClassLoader()));
+      loader = loadersMap.get(extension);
     }
     return loader;
   }
diff --git a/server/src/test/java/io/druid/initialization/InitializationTest.java b/server/src/test/java/io/druid/initialization/InitializationTest.java
index 8209d68d34a..3d978dcdb92 100644
--- a/server/src/test/java/io/druid/initialization/InitializationTest.java
+++ b/server/src/test/java/io/druid/initialization/InitializationTest.java
@@ -113,7 +113,8 @@ public class InitializationTest
   @Test
   public void test04DuplicateClassLoaderExtensions() throws Exception
   {
-    Initialization.getLoadersMap().put("xyz", (URLClassLoader) Initialization.class.getClassLoader());
+    final File extensionDir = temporaryFolder.newFolder();
+    Initialization.getLoadersMap().put(extensionDir, (URLClassLoader) Initialization.class.getClassLoader());
 
     Collection<DruidModule> modules = Initialization.getFromExtensions(new ExtensionsConfig(), DruidModule.class);
 
@@ -426,6 +427,29 @@ public class InitializationTest
 
   }
 
+  @Test
+  public void testExtensionsWithSameDirName() throws Exception
+  {
+    final String extensionName = "some_extension";
+    final File tmpDir1 = temporaryFolder.newFolder();
+    final File tmpDir2 = temporaryFolder.newFolder();
+    final File extension1 = new File(tmpDir1, extensionName);
+    final File extension2 = new File(tmpDir2, extensionName);
+    Assert.assertTrue(extension1.mkdir());
+    Assert.assertTrue(extension2.mkdir());
+    final File jar1 = new File(extension1, "jar1.jar");
+    final File jar2 = new File(extension2, "jar2.jar");
+
+    Assert.assertTrue(jar1.createNewFile());
+    Assert.assertTrue(jar2.createNewFile());
+
+    final ClassLoader classLoader1 = Initialization.getClassLoaderForExtension(extension1);
+    final ClassLoader classLoader2 = Initialization.getClassLoaderForExtension(extension2);
+
+    Assert.assertArrayEquals(new URL[]{jar1.toURL()}, ((URLClassLoader) classLoader1).getURLs());
+    Assert.assertArrayEquals(new URL[]{jar2.toURL()}, ((URLClassLoader) classLoader2).getURLs());
+  }
+
   public static class TestDruidModule implements DruidModule
   {
     @Override