diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index dc45c0211353..03e1d3610333 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -41,7 +41,7 @@ blackhole_timeout - INTEGER (seconds)
 	MPTCP is re-enabled and will reset to the initial value when the
 	blackhole issue goes away.
 
-	0 to disable the blackhole detection.
+	0 to disable the blackhole detection. This is a per-namespace sysctl.
 
 	Default: 3600