diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index e5bf97a188..26ddfe633c 100644
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -929,6 +929,9 @@ func (e *ExitError) Error() string {
 // If any of c.Stdin, c.Stdout or c.Stderr are not an [*os.File], Wait also waits
 // for the respective I/O loop copying to or from the process to complete.
 //
+// Wait must not be called concurrently from multiple goroutines.
+// A custom Cmd.Cancel function should not call Wait.
+//
 // Wait releases any resources associated with the [Cmd].
 func (c *Cmd) Wait() error {
 	if c.Process == nil {