diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 2e1a0960d7d..427b3c41e3a 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -4870,7 +4870,7 @@ Only works for Bourne-like shells."
 	(tramp-compat-funcall
 	 'tramp-send-command
 	 (process-get proc 'vector)
-	 (format "kill -2 %d" pid))
+	 (format "kill -2 -%d" pid))
 	;; Wait, until the process has disappeared.  If it doesn't,
 	;; fall back to the default implementation.
 	(with-timeout (1 (ignore))