diff -r 5be0a162ed89 -r 06a22aed06d1 jdk/src/macosx/classes/java/util/prefs/MacOSXPreferences.java
--- a/jdk/src/macosx/classes/java/util/prefs/MacOSXPreferences.java	Tue Apr 24 14:59:45 2012 -0700
+++ b/jdk/src/macosx/classes/java/util/prefs/MacOSXPreferences.java	Wed Apr 25 12:31:31 2012 -0700
@@ -25,6 +25,8 @@
 
 package java.util.prefs;
 
+import java.util.Objects;
+
 class MacOSXPreferences extends AbstractPreferences {
     // fixme need security checks?
 
@@ -147,6 +149,7 @@
     // AbstractPreferences implementation
     protected void removeSpi(String key)
     {
+        Objects.requireNonNull(key, "Specified key cannot be null");
         file.removeKeyFromNode(path, key);
     }