diff --git a/bootstrap/src/exec.rs b/bootstrap/src/exec.rs
index 7c96927a48..fdf781b54c 100644
--- a/bootstrap/src/exec.rs
+++ b/bootstrap/src/exec.rs
@@ -314,11 +314,15 @@ pub(crate) fn spawn(
         }
         // Continue serving the scheme as the child.
         Ok(0) => {
+            let _ = libredox::call::write(1, b"SP:0\n");
             drop(read);
+            let _ = libredox::call::write(1, b"SP:1\n");
 
             let socket = Socket::create_inner(scheme_creation_cap.as_raw_fd(), nonblock)
                 .expect("failed to open proc scheme socket");
+            let _ = libredox::call::write(1, b"SP:2\n");
             drop(scheme_creation_cap);
+            let _ = libredox::call::write(1, b"SP:3\n");
 
             inner(write, socket, auth, kernel_schemes)
         }