diff --git a/core/src/main/java/edu/umd/cs/piccolo/event/PInputEventFilter.java b/core/src/main/java/edu/umd/cs/piccolo/event/PInputEventFilter.java
index c86ead9..de9f98b 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/event/PInputEventFilter.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/event/PInputEventFilter.java
@@ -53,7 +53,7 @@
  */
 public class PInputEventFilter {
 
-    public static final int ALL_MODIFIERS_MASK = InputEvent.BUTTON1_MASK | InputEvent.BUTTON2_MASK
+    public static int ALL_MODIFIERS_MASK = InputEvent.BUTTON1_MASK | InputEvent.BUTTON2_MASK
             | InputEvent.BUTTON3_MASK | InputEvent.SHIFT_MASK | InputEvent.CTRL_MASK | InputEvent.ALT_MASK
             | InputEvent.ALT_GRAPH_MASK | InputEvent.META_MASK;
 
diff --git a/core/src/main/java/edu/umd/cs/piccolo/util/PUtil.java b/core/src/main/java/edu/umd/cs/piccolo/util/PUtil.java
index 8b8f11d..26ca50f 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/util/PUtil.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/util/PUtil.java
@@ -58,8 +58,8 @@
     public static int ACTIVITY_SCHEDULER_FRAME_DELAY = 10;
     private static final int PATH_IS_DONE = -1;
 
-    public static final Iterator NULL_ITERATOR = Collections.EMPTY_LIST.iterator();
-    public static final Enumeration NULL_ENUMERATION = new Enumeration() {
+    public static Iterator NULL_ITERATOR = Collections.EMPTY_LIST.iterator();
+    public static Enumeration NULL_ENUMERATION = new Enumeration() {
         public boolean hasMoreElements() {
             return false;
         }
@@ -69,7 +69,7 @@
         }
     };
 
-    public static final OutputStream NULL_OUTPUT_STREAM = new OutputStream() {
+    public static OutputStream NULL_OUTPUT_STREAM = new OutputStream() {
         public void close() {
         }