diff --git a/src/jvm/clojure/lang/SeqIterator.java b/src/jvm/clojure/lang/SeqIterator.java
index e6ad481..7b6a393 100644
--- a/src/jvm/clojure/lang/SeqIterator.java
+++ b/src/jvm/clojure/lang/SeqIterator.java
@@ -39,6 +39,10 @@ public boolean hasNext(){
 		}
 	else if(seq == next)
 		next = RT.next(seq);
+	else if (RT.seq(next) == null)
+		System.out.println("this shouldn't happen: " + (this == seq));
+	if (RT.seq(next) == null && next != null)
+		System.out.println("bug: " + next);
 	return next != null;
 }
 

Add Nicola Mometto's patch showing weird stuff at source of problem
Add Nicola Mometto's patch showing weird stuff at source of problem
