diff --git a/platform/extensions/src/com/intellij/openapi/extensions/impl/ExtensionPointImpl.java b/platform/extensions/src/com/intellij/openapi/extensions/impl/ExtensionPointImpl.java
index 14b54ec96dcd..ca6d3000a874 100644
--- a/platform/extensions/src/com/intellij/openapi/extensions/impl/ExtensionPointImpl.java
+++ b/platform/extensions/src/com/intellij/openapi/extensions/impl/ExtensionPointImpl.java
@@ -197,7 +197,7 @@ public class ExtensionPointImpl<T> implements ExtensionPoint<T> {
         }
       }
     }
-    return result;
+    return result.length == 0 ? result : result.clone();
   }
 
   @Override
diff --git a/platform/extensions/testSrc/com/intellij/openapi/extensions/impl/ExtensionPointImplTest.java b/platform/extensions/testSrc/com/intellij/openapi/extensions/impl/ExtensionPointImplTest.java
index f9065c061786..6db6a2f9da07 100644
--- a/platform/extensions/testSrc/com/intellij/openapi/extensions/impl/ExtensionPointImplTest.java
+++ b/platform/extensions/testSrc/com/intellij/openapi/extensions/impl/ExtensionPointImplTest.java
@@ -24,6 +24,7 @@ import org.junit.After;
 import org.junit.Test;
 import org.picocontainer.defaults.DefaultPicoContainer;
 
+import java.util.Arrays;
 import java.util.List;
 
 import static org.hamcrest.Matchers.*;
@@ -248,6 +249,20 @@ public class ExtensionPointImplTest {
     assertThat(ourTestLog.errors(), empty());
   }
 
+  @Test
+  public void clientsCannotModifyCachedExtensions() {
+    ExtensionPoint<Integer> extensionPoint = buildExtensionPoint(Integer.class);
+    extensionPoint.registerExtension(4);
+    extensionPoint.registerExtension(2);
+
+    Integer[] extensions = extensionPoint.getExtensions();
+    assertEquals(ContainerUtil.newArrayList(4, 2), Arrays.asList(extensions));
+    Arrays.sort(extensions);
+    assertEquals(ContainerUtil.newArrayList(2, 4), Arrays.asList(extensions));
+
+    assertEquals(ContainerUtil.newArrayList(4, 2), Arrays.asList(extensionPoint.getExtensions()));
+  }
+
   private static <T> ExtensionPoint<T> buildExtensionPoint(Class<T> aClass) {
     return new ExtensionPointImpl<T>(
       ExtensionsImplTest.EXTENSION_POINT_NAME_1, aClass.getName(), ExtensionPoint.Kind.INTERFACE,