--- a/graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/type/AbstractObjectStamp.java	Thu Apr 30 11:30:46 2015 +0200
+++ b/graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/type/AbstractObjectStamp.java	Thu Apr 30 13:17:09 2015 +0200
@@ -205,7 +205,8 @@
                 } else {
                     joinType = null;
                 }
-                if (joinExactType || (!type.isInterface() && !other.type.isInterface())) {
+
+                if (joinExactType || (!isInterfaceOrArrayOfInterface(type) && !isInterfaceOrArrayOfInterface(other.type))) {
                     joinAlwaysNull = true;
                 }
             }
@@ -231,6 +232,10 @@
         }
     }
 
+    private static boolean isInterfaceOrArrayOfInterface(ResolvedJavaType t) {
+        return t.isInterface() || (t.isArray() && t.getElementalType().isInterface());
+    }
+
     public static boolean isConcreteType(ResolvedJavaType type) {
         return !(type.isAbstract() && !type.isArray());
     }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.jtt/src/com/oracle/graal/jtt/bytecode/BC_checkcast03.java	Thu Apr 30 13:17:09 2015 +0200
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.graal.jtt.bytecode;
+
+import org.junit.*;
+
+import com.oracle.graal.jtt.*;
+
+/**
+ * Tests the checkcast works, when casting an array of interface.
+ */
+public class BC_checkcast03 extends JTTTest {
+
+    public interface IObject {
+
+    }
+
+    private static class BaseClass {
+
+    }
+
+    private static class TestClass extends BaseClass implements IObject {
+    }
+
+    static TestClass[] a1 = {new TestClass()};
+
+    public static BaseClass[] getBaseClassArray() {
+        return a1;
+    }
+
+    public static IObject[] test() {
+        return (IObject[]) getBaseClassArray();
+    }
+
+    @Test
+    public void run0() throws Throwable {
+        runTest("test");
+    }
+}