p-Tag added when using wpp

When using following code, wpp adds a <p> in html. Could you please tell me how to stop this or is it a bug?

<br />
[wpp limit="3" range="all" stats_date=1 stats_date_format='j. F Y' stats_comments=1 stats_views=0 post_type=post order_by="views" thumbnail_width=261 thumbnail_height=168 excerpt_length=20 excerpt_by_words=1 excerpt_format=0 wpp_start="<li class="popular_posts">" wpp_end="" post_html='<li class="popular_posts">{thumb}<h4 class="top"><a href="{url}">{text_title}</a></h4><li class="meta">{stats}
<li><h4>{summary}</h4></li>
']<br />

Output (snipped):

<br />
<!-- WordPress Popular Posts Plugin v3.0.3 [SC] [weekly] [views] [custom] --><br />
<ul class="wpp-list"><br />
<li class="popular_posts"><a href="...."><br />
<img src="..." /></a><br />
<h4 class="top"><a href="#">...</a></h4><br />
<li class="meta"><span class="wpp-date">7. Juni 2014</span> | <span class="wpp-comments">0 Kommentare</span></p>
<li>
<h4>...</h4>
</li>
<p><p><br />
</p><br />