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 9639b7a..0c2dbe5 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
@@ -104,11 +104,13 @@
         if (aEvent.isHandled() && !acceptsAlreadyHandledEvents) 
             return false;
         
-        if ((modifiers & andMask) != andMask || (modifiers & notMask) != 0)
-            return false;
-                                                    
-        if (orMask != ALL_MODIFIERS_MASK && (modifiers & orMask) == 0)
-            return false;
+        if (modifiers != 0) {
+            if ((modifiers & andMask) != andMask || (modifiers & notMask) != 0)
+                return false;
+                                                        
+            if (orMask != ALL_MODIFIERS_MASK && (modifiers & orMask) == 0)
+                return false;
+        }
         
         if (aEvent.isMouseEvent() && clickCount != -1 && clickCount != aEvent.getClickCount()) 
             return false;
diff --git a/core/src/test/java/edu/umd/cs/piccolo/event/PInputEventFilterTest.java b/core/src/test/java/edu/umd/cs/piccolo/event/PInputEventFilterTest.java
index 3e6629b..af4a8db 100644
--- a/core/src/test/java/edu/umd/cs/piccolo/event/PInputEventFilterTest.java
+++ b/core/src/test/java/edu/umd/cs/piccolo/event/PInputEventFilterTest.java
@@ -207,7 +207,7 @@
     }
 
     private PInputEvent buildTestEvent() {
-        return buildTestEvent(0);
+        return buildTestEvent(InputEvent.BUTTON1_MASK);
     }
 
     private PInputEvent buildTestEvent(int modifiers) {