diff --git a/core/util.inc.php b/core/util.inc.php
index 1f653574..fa2758d8 100644
--- a/core/util.inc.php
+++ b/core/util.inc.php
@@ -180,6 +180,23 @@ function plural($num, $single_form="", $plural_form="s") {
 	return ($num == 1) ? $single_form : $plural_form;
 }
 
+/**
+ * Give a HTML string which shows an IP (if the user is allowed to see IPs),
+ * and a link to ban that IP (if the user is allowed to ban IPs)
+ *
+ * FIXME: also check that IP ban ext is installed
+ *
+ * @retval string
+ */
+function show_ip($ip, $ban_reason) {
+	global $user;
+	$u_reason = url_escape($ban_reason);
+	$u_end = url_escape("+1 week");
+	$ban = $user->can("ban_ip") ? ", <a href='".make_link("ip_ban/list", "ip=$ip&reason=$u_reason&end=$u_end#add")."'>Ban</a>" : "";
+	$ip = $user->can("view_ip") ? $ip.$ban : "";
+	return $ip;
+}
+
 
 /**
  * Different databases have different ways to represent booleans; this
diff --git a/ext/comment/theme.php b/ext/comment/theme.php
index 54e5938b..ed831dad 100644
--- a/ext/comment/theme.php
+++ b/ext/comment/theme.php
@@ -174,8 +174,7 @@ class CommentListTheme extends Themelet {
 				$avatar = "<img src=\"http://www.gravatar.com/avatar/$hash.jpg\"><br>";
 			}
 			$h_reply = " - <a href='javascript: replyTo($i_image_id, $i_comment_id)'>Reply</a>";
-			$ban = $user->can("ban_ip") ? ", <a href='".make_link("ip_ban/list", "ip={$h_poster_ip}&reason=Comment%20posted%20{$comment->posted}#add")."'>Ban</a>" : "";
-			$h_ip = $user->can("view_ip") ? "<br>$h_poster_ip, $ban" : "";
+			$h_ip = $user->can("view_ip") ? "<br>".show_ip($image->owner_ip, "Comment posted {$comment->posted}") : "";
 			$h_del = $user->can("delete_comment") ?
 				' - <a onclick="return confirm(\'Delete comment by '.$h_name.':\\n'.$stripped_nonl.'\');" '.
 				'href="'.make_link('comment/delete/'.$i_comment_id.'/'.$i_image_id).'">Del</a>' : '';
diff --git a/ext/tag_edit/theme.php b/ext/tag_edit/theme.php
index 5d598de6..cee7268b 100644
--- a/ext/tag_edit/theme.php
+++ b/ext/tag_edit/theme.php
@@ -37,8 +37,7 @@ class TagEditTheme extends Themelet {
 		$h_owner = html_escape($image->get_owner()->name);
 		$h_av = $image->get_owner()->get_avatar_html();
 		$h_date = autodate($image->posted);
-		$ban = $user->can("ban_ip") ? ", <a href='".make_link("ip_ban/list", "ip={$image->owner_ip}&reason=Image%20posted%20{$image->posted}#add")."'>Ban</a>" : "";
-		$ip = $user->can("view_ip") ? " ({$image->owner_ip}$ban)" : "";
+		$ip = $user->can("view_ip") ? " (".show_ip($image->owner_ip, "Image posted {$image->posted}").")" : "";
 		return "
 			<tr>
 				<td>User</td>