--- a/jdk/src/java.desktop/share/classes/javax/swing/JInternalFrame.java	Thu Jul 30 15:27:02 2015 +0300
+++ b/jdk/src/java.desktop/share/classes/javax/swing/JInternalFrame.java	Thu Jul 30 19:10:23 2015 +0300
@@ -1247,6 +1247,7 @@
      *
      * @param layer  an <code>Integer</code> object specifying this
      *          frame's desktop layer
+     * @throws NullPointerException if {@code layer} is {@code null}
      * @see JLayeredPane
      * @beaninfo
      *     expert: true

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/javax/swing/JInternalFrame/SetLayerNPE/SetLayerNPE.java	Thu Jul 30 19:10:23 2015 +0300
@@ -0,0 +1,55 @@
+/*
+ * 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.
+ */
+
+import java.awt.EventQueue;
+
+import javax.swing.JDesktopPane;
+import javax.swing.JInternalFrame;
+
+/**
+ * @test
+ * @bug 6206439
+ */
+public final class SetLayerNPE {
+
+    public static void main(final String[] args) throws Exception {
+        EventQueue.invokeAndWait(() -> {
+            try {
+                // JInternalFrame without parent
+                new JInternalFrame("My Frame").setLayer(null);
+                throw new AssertionError("expected NPE was not thrown");
+            } catch (final NullPointerException ignored) {
+            }
+        });
+        EventQueue.invokeAndWait(() -> {
+            try {
+                // JInternalFrame with parent
+                JInternalFrame jif = new JInternalFrame("My Frame");
+                new JDesktopPane().add(jif);
+                jif.setLayer(null);
+                throw new AssertionError("expected NPE was not thrown");
+            } catch (final NullPointerException ignored) {
+            }
+        });
+    }
+}