diff --git a/src/context/context.go b/src/context/context.go
index 0f36881b1e..05d01d0294 100644
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -220,6 +220,7 @@ func TODO() Context {
 
 // A CancelFunc tells an operation to abandon its work.
 // A CancelFunc does not wait for the work to stop.
+// A CancelFunc may be called by multiple goroutines simultaneously.
 // After the first call, subsequent calls to a CancelFunc do nothing.
 type CancelFunc func()