private boolean parseAfterThousand(){
        // If no more tokens, it's still valid
        if (peek() == null){
            return true;
        }
        
        //note, this consumes, so peek isn't exactly the same
        int[] parsed = parsePrefix();
        if (parsed == null){
            // Error parsing
            return false;
        }
        
        if (peek() == null){
            units = parsed;
            return true;
        }
        
        em.error("Expected end of file; got \"%s\"", peek());
        return false;
    }