diff --git a/html/inc/text_transform.inc b/html/inc/text_transform.inc
index 9d0c41aa07..05026129a7 100644
--- a/html/inc/text_transform.inc
+++ b/html/inc/text_transform.inc
@@ -153,12 +153,12 @@ function bb2html($text) {
 		"<b>\\1</b>",
 		"<i>\\1</i>",
 		"<u>\\1</u>",
-		"<a href=\"https://\\1\">\\2</a>",
-		"<a href=\"https://\\1\">https://\\1</a>",
-		"<a href=\"http://\\2\">\\3</a>",
-		"<a href=\"http://\\2\">http://\\2</a>",
-		"<a href=\"http://\\2\">\\3</a>",
-		"<a href=\"http://\\2\">http://\\2</a>",
+		"<a href=\"https://\\1\" rel=\"nofollow\">\\2</a>",
+		"<a href=\"https://\\1\" rel=\"nofollow\">https://\\1</a>",
+		"<a href=\"http://\\2\" rel=\"nofollow\">\\3</a>",
+		"<a href=\"http://\\2\" rel=\"nofollow\">http://\\2</a>",
+		"<a href=\"http://\\2\" rel=\"nofollow\">\\3</a>",
+		"<a href=\"http://\\2\" rel=\"nofollow\">http://\\2</a>",
         "<div style='font-style: oblique'>\\1 wrote:</div><blockquote class='postbody'>\\2</blockquote>",
         "<blockquote class='postbody'>\\1</blockquote>",
 		"<font face=\\1>\\2</font>",