diff --git a/cmd/stress/stress.go b/cmd/stress/stress.go
index f02fa2a7..e0ff6b4c 100644
--- a/cmd/stress/stress.go
+++ b/cmd/stress/stress.go
@@ -2,6 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// TODO: syscall.SIGABRT is not defined for Plan 9 (issue #11975)
+
+// +build !plan9
+
 // The stress utility is intended for catching of episodic failures.
 // It runs a given process in parallel in a loop and collects any failures.
 // Usage: