diff --git a/src/share/classes/java/awt/Robot.java b/src/share/classes/java/awt/Robot.java
index f7a40c740bc00c80ac7831ed9d63c08dc0fd411b..1233c291a3ef906ce095f40f2adac8e4700854fb 100644
--- a/src/share/classes/java/awt/Robot.java
+++ b/src/share/classes/java/awt/Robot.java
@@ -70,7 +70,7 @@ public class Robot {
     private RobotPeer peer;
     private boolean isAutoWaitForIdle = false;
     private int autoDelay = 0;
-    private static int LEGAL_BUTTON_MASK;
+    private static int LEGAL_BUTTON_MASK = 0;
 
     // location of robot's GC, used in mouseMove(), getPixelColor() and captureScreenImage()
     private Point gdLoc;
@@ -95,23 +95,6 @@ public class Robot {
         }
         init(GraphicsEnvironment.getLocalGraphicsEnvironment()
             .getDefaultScreenDevice());
-        int tmpMask = 0;
-
-        if (Toolkit.getDefaultToolkit().areExtraMouseButtonsEnabled()){
-            if (Toolkit.getDefaultToolkit() instanceof SunToolkit) {
-                final int buttonsNumber = ((SunToolkit)(Toolkit.getDefaultToolkit())).getNumberOfButtons();
-                for (int i = 0; i < buttonsNumber; i++){
-                    tmpMask |= InputEvent.getMaskForButton(i+1);
-                }
-            }
-        }
-        tmpMask |= InputEvent.BUTTON1_MASK|
-            InputEvent.BUTTON2_MASK|
-            InputEvent.BUTTON3_MASK|
-            InputEvent.BUTTON1_DOWN_MASK|
-            InputEvent.BUTTON2_DOWN_MASK|
-            InputEvent.BUTTON3_DOWN_MASK;
-        LEGAL_BUTTON_MASK = tmpMask;
     }
 
     /**
@@ -156,6 +139,28 @@ public class Robot {
             disposer = new RobotDisposer(peer);
             sun.java2d.Disposer.addRecord(anchor, disposer);
         }
+        initLegalButtonMask();
+    }
+
+    private static synchronized void initLegalButtonMask() {
+        if (LEGAL_BUTTON_MASK != 0) return;
+
+        int tmpMask = 0;
+        if (Toolkit.getDefaultToolkit().areExtraMouseButtonsEnabled()){
+            if (Toolkit.getDefaultToolkit() instanceof SunToolkit) {
+                final int buttonsNumber = ((SunToolkit)(Toolkit.getDefaultToolkit())).getNumberOfButtons();
+                for (int i = 0; i < buttonsNumber; i++){
+                    tmpMask |= InputEvent.getMaskForButton(i+1);
+                }
+            }
+        }
+        tmpMask |= InputEvent.BUTTON1_MASK|
+            InputEvent.BUTTON2_MASK|
+            InputEvent.BUTTON3_MASK|
+            InputEvent.BUTTON1_DOWN_MASK|
+            InputEvent.BUTTON2_DOWN_MASK|
+            InputEvent.BUTTON3_DOWN_MASK;
+        LEGAL_BUTTON_MASK = tmpMask;
     }
 
     /* determine if the security policy allows Robot's to be created */
diff --git a/test/java/awt/Robot/CtorTest/CtorTest.java b/test/java/awt/Robot/CtorTest/CtorTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..ea9c56fa2d552b2d0bdb3ba76a3c555620597e14
--- /dev/null
+++ b/test/java/awt/Robot/CtorTest/CtorTest.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+  @test
+  @bug 6855323
+  @summary  Robot(GraphicsDevice) constructor initializes LEGAL_BUTTON_MASK variable improperly
+  @author Dmitry Cherepanov area=awt.robot
+  @run main CtorTest
+*/
+
+/**
+ * CtorRobot.java
+ *
+ * summary: creates Robot using one parameter constructor
+ */
+
+import java.awt.*;
+import java.awt.event.*;
+
+import sun.awt.SunToolkit;
+
+public class CtorTest
+{
+    public static void main(String []s) throws Exception
+    {
+        // one parameter constructor
+        GraphicsDevice graphicsDevice = GraphicsEnvironment.
+            getLocalGraphicsEnvironment().getDefaultScreenDevice();
+        Robot robot = new Robot(graphicsDevice);
+        clickOnFrame(robot);
+    }
+
+    // generate mouse events
+    private static void clickOnFrame(Robot robot) {
+        Frame frame = new Frame();
+        frame.setBounds(100, 100, 100, 100);
+        frame.setVisible(true);
+
+        ((SunToolkit)Toolkit.getDefaultToolkit()).realSync();
+
+        // click in the middle of the frame
+        robot.mouseMove(150, 150);
+        robot.delay(50);
+        robot.mousePress(InputEvent.BUTTON1_MASK);
+        robot.delay(50);
+        robot.mouseRelease(InputEvent.BUTTON1_MASK);
+
+        ((SunToolkit)Toolkit.getDefaultToolkit()).realSync();
+    }
+}