diff --git a/src/java.desktop/unix/classes/sun/awt/X11GraphicsEnvironment.java b/src/java.desktop/unix/classes/sun/awt/X11GraphicsEnvironment.java
index 5c9d2a1b695..93f5eaf6656 100644
--- a/src/java.desktop/unix/classes/sun/awt/X11GraphicsEnvironment.java
+++ b/src/java.desktop/unix/classes/sun/awt/X11GraphicsEnvironment.java
@@ -236,7 +236,7 @@ private synchronized void initDevices() {
             throw new AWTError("no screen devices");
         }
         int index = getDefaultScreenNum();
-        mainScreen = 0 < index && index < screens.length ? index : 0;
+        mainScreen = 0 < index && index < numScreens ? index : 0;
 
         for (int id = 0; id < numScreens; ++id) {
             devices.put(id, old.containsKey(id) ? old.remove(id) :