diff --git a/ChangeLog b/ChangeLog
index 24ca9e9a..ad48983e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -133,6 +133,10 @@
 	* twittering-mode.el (twittering-extract-timeline-spec): Fix the
 	regexp for "search" timeline spec; same as for "filter".
 
+	* twittering-mode.el (twittering-make-clickable-status-datum):
+	When trying to add a text property to `source', check it is
+	non-nil first for avoiding an error caused by `string-match'.
+
 2010-02-07  Tadashi MATSUO  <tad@mymail.twin.jp>
 
 	* test/test-twittering-mode.el (test-format-status): replace the
diff --git a/twittering-mode.el b/twittering-mode.el
index d1f5733b..fa0f4ed4 100644
--- a/twittering-mode.el
+++ b/twittering-mode.el
@@ -2038,7 +2038,8 @@ If ID of STATUS-DATUM is already in ID-TABLE, return nil. If not, return t."
 	    (setq regexp-index (match-end 0)))))
 
       ;; make source pretty and clickable
-      (if (string-match "<a href=\"\\(.*?\\)\".*?>\\(.*\\)</a>" source)
+      (if (and source
+	       (string-match "<a href=\"\\(.*?\\)\".*?>\\(.*\\)</a>" source))
 	  (let ((uri (match-string-no-properties 1 source))
 		(caption (match-string-no-properties 2 source)))
 	    (setq source caption)
@@ -2049,7 +2050,7 @@ If ID of STATUS-DATUM is already in ID-TABLE, return nil. If not, return t."
 			  face twittering-uri-face
 			  source ,source)
 	     source)
-	    (add-to-list 'status (cons 'source  source))
+	    (add-to-list 'status (cons 'source source))
 	    ))
 
       ;; make hashtag in text clickable