diff --git a/asterix-om/src/main/java/edu/uci/ics/asterix/om/types/AUnionType.java b/asterix-om/src/main/java/edu/uci/ics/asterix/om/types/AUnionType.java
index 4e77e0d..4ba5a4c 100644
--- a/asterix-om/src/main/java/edu/uci/ics/asterix/om/types/AUnionType.java
+++ b/asterix-om/src/main/java/edu/uci/ics/asterix/om/types/AUnionType.java
@@ -27,7 +27,7 @@
     }
 
     public boolean isNullableType() {
-        return unionList.size() == 2 && unionList.get(0).equals(BuiltinType.ANULL);
+    	return unionList.size() == 2 && unionList.get(0).getTypeTag().equals(BuiltinType.ANULL.getTypeTag());
     }
 
     @Override