--- a/.emacs-my	Mon Apr 08 01:00:32 2013 +0300
+++ b/.emacs-my	Thu Apr 11 00:09:28 2013 +0300
@@ -1672,15 +1672,19 @@
      (add-hook 'message-sent-hook 'gnus-score-followup-thread)
      ))
 
+(defvar my-gnus-summary-kill-same-subject-min-len 8
+  "Minimal length of subject string to ignore this subject.")
 (defun my-gnus-summary-kill-same-subject (&optional unmark)
   "Add negative scores for all articles with same subject."
   (interactive "P")
   (when (or (not (integerp unmark)) (< 0 unmark))
-    (gnus-summary-score-entry
-     "subject" (gnus-simplify-subject-fuzzy (gnus-summary-article-subject))
-     's (- gnus-score-interactive-default-score) (current-time-string)))
+    (let ( (subj (gnus-simplify-subject-fuzzy (gnus-summary-article-subject))) )
+      (when (<= (length subj) my-gnus-summary-kill-same-subject-min-len)
+        (gnus-summary-score-entry
+         "subject" subj
+         's (- gnus-score-interactive-default-score) (current-time-string)))))
   (gnus-summary-kill-same-subject unmark))
-(eval-after-load 'gnus-summary
+(eval-after-load 'gnus-sum
   '(define-key gnus-summary-mode-map (kbd "C-k") #'my-gnus-summary-kill-same-subject))
 
 (defun my-gnus-thread-score-function (&rest scores)