diff --git a/classes/Notice.php b/classes/Notice.php
index 5e1f83a52f..06750b4363 100644
--- a/classes/Notice.php
+++ b/classes/Notice.php
@@ -54,10 +54,13 @@ class Notice extends DB_DataObject
 
 	function saveTags() {
 		/* extract all #hastags */
-		$count = preg_match_all('/(?:^|\s)#([A-Za-z0-9]{1,64})/', strtolower($this->content), $match);
+		$count = preg_match_all('/(?:^|\s)#([A-Za-z0-9_\-\.]{1,64})/', strtolower($this->content), $match);
 		if (!$count) {
 			return true;
 		}
+		
+		/* elide characters we don't want in the tag */
+		$match[1] = str_replace(array('-', '_', '.'), '', $match[1]);
 
 		/* Add them to the database */
 		foreach(array_unique($match[1]) as $hashtag) {
diff --git a/lib/util.php b/lib/util.php
index 469bc986fe..1530092126 100644
--- a/lib/util.php
+++ b/lib/util.php
@@ -688,16 +688,16 @@ function common_render_content($text, $notice) {
 	$r = preg_replace('@https?://[^)\]>\s]+@', '<a href="\0" class="extlink">\0</a>', $r);
 	$r = preg_replace('/(^|\s+)@([a-z0-9]{1,64})/e', "'\\1@'.common_at_link($id, '\\2')", $r);
 	$r = preg_replace('/^T ([A-Z0-9]{1,64}) /e', "'T '.common_at_link($id, '\\1').' '", $r);
-	$r = preg_replace('/(^|\s+)#([A-Za-z0-9]{1,64})/e', "'\\1#'.common_tag_link('\\2')", $r);
+	$r = preg_replace('/(^|\s+)#([A-Za-z0-9_\-\.]{1,64})/e', "'\\1#'.common_tag_link('\\2')", $r);
 	# XXX: machine tags
 	return $r;
 }
 
 function common_tag_link($tag) {
 	if(common_config('site', 'fancy')) {
-		return '<a href="' . htmlspecialchars(common_path('tag/' . strtolower($tag))) . '" rel="tag" class="hashlink">' . htmlspecialchars($tag) . '</a>';
+		return '<a href="' . htmlspecialchars(common_path('tag/' . strtolower(str_replace(array('-', '_', '.'), '', $tag)))) . '" rel="tag" class="hashlink">' . htmlspecialchars($tag) . '</a>';
 	} else {
-		return '<a href="' . htmlspecialchars(common_path('index.php?action=tag&tag=' . strtolower($tag))) . '" rel="tag" class="hashlink">' . htmlspecialchars($tag) . '</a>';
+		return '<a href="' . htmlspecialchars(common_path('index.php?action=tag&tag=' . strtolower(str_replace(array('-', '_', '.'), '', $tag)))) . '" rel="tag" class="hashlink">' . htmlspecialchars($tag) . '</a>';
 	}
 }