diff --git a/src/share/classes/java/awt/AlphaComposite.java b/src/share/classes/java/awt/AlphaComposite.java
index 622690cddef4cb6d4e467d17d09e04feabf182ae..978d9da2948003bb4130f38845ec3beb1d259466 100644
--- a/src/share/classes/java/awt/AlphaComposite.java
+++ b/src/share/classes/java/awt/AlphaComposite.java
@@ -614,14 +614,15 @@ public final class AlphaComposite implements Composite {
     }
 
     private AlphaComposite(int rule, float alpha) {
-        if (alpha < 0.0f || alpha > 1.0f) {
-            throw new IllegalArgumentException("alpha value out of range");
-        }
         if (rule < MIN_RULE || rule > MAX_RULE) {
             throw new IllegalArgumentException("unknown composite rule");
         }
-        this.rule = rule;
-        this.extraAlpha = alpha;
+        if (alpha >= 0.0f && alpha <= 1.0f) {
+            this.rule = rule;
+            this.extraAlpha = alpha;
+        } else {
+            throw new IllegalArgumentException("alpha value out of range");
+        }
     }
 
     /**
diff --git a/src/share/classes/sun/font/SunFontManager.java b/src/share/classes/sun/font/SunFontManager.java
index a10c549532b9412ffd07e22d8361b68ebc8e8672..923f1cc475bd9b8b44168b6a142bde30ad7b8920 100644
--- a/src/share/classes/sun/font/SunFontManager.java
+++ b/src/share/classes/sun/font/SunFontManager.java
@@ -3058,7 +3058,7 @@ public abstract class SunFontManager implements FontSupport, FontManagerForSGE {
             return;
         }
         /* Use lock specific to the font system */
-        synchronized (lucidaFontName) {
+        synchronized (this) {
             if (FontUtilities.debugFonts()) {
                 Thread.dumpStack();
                 FontUtilities.getLogger()
@@ -3194,7 +3194,7 @@ public abstract class SunFontManager implements FontSupport, FontManagerForSGE {
             return;
         }
         /* Use lock specific to the font system */
-        synchronized (lucidaFontName) {
+        synchronized (this) {
             if (FontUtilities.debugFonts()) {
                 Thread.dumpStack();
                 FontUtilities.getLogger().info("loadAllFontFiles() called");
diff --git a/test/java/awt/AlphaComposite/TestAlphaCompositeForNaN.java b/test/java/awt/AlphaComposite/TestAlphaCompositeForNaN.java
new file mode 100644
index 0000000000000000000000000000000000000000..2b9fb6e2f2e57d85020d55e926b38c9afaf027d6
--- /dev/null
+++ b/test/java/awt/AlphaComposite/TestAlphaCompositeForNaN.java
@@ -0,0 +1,22 @@
+/*
+ * @test
+ * @bug 6918065
+ * @summary Test for passing NaN as alpha
+ *          should throw IllegalArgumentException
+ */
+
+import java.awt.*;
+
+public class TestAlphaCompositeForNaN {
+  public static void main(String[] args) {
+    try {
+      AlphaComposite a = AlphaComposite.getInstance(AlphaComposite.DST, Float.NaN);
+      System.out.println("Failed");
+      throw new RuntimeException(a + " failed to throw IllegalArgumentException for alpha = " + Float.NaN);
+    }
+    catch (IllegalArgumentException ie) {
+      System.out.println("Passed");
+      System.out.println("Caught " + ie);
+    }
+  }
+}