--- tool/src/main/java/org/antlr/tool/CompositeGrammar.java.orig	2014-08-06 22:00:42.002467314 +0000
+++ tool/src/main/java/org/antlr/tool/CompositeGrammar.java	2014-08-06 22:01:03.772111735 +0000
@@ -31,7 +31,15 @@
 import org.antlr.analysis.NFAState;
 import org.antlr.misc.Utils;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.Vector;
 import org.antlr.grammar.v2.AssignTokenTypesWalker;
 
 /** A tree of component (delegate) grammars.
@@ -219,8 +227,10 @@
 	public List<Grammar> getIndirectDelegates(Grammar g) {
 		List<Grammar> direct = getDirectDelegates(g);
 		List<Grammar> delegates = getDelegates(g);
-		delegates.removeAll(direct);
-		return delegates;
+                if ( direct!=null ) {
+                        delegates.removeAll(direct);
+                }
+                return delegates;
 	}
 
 	/** Return list of delegate grammars from root down to g.