diff --git a/client/internal/certproof/helper_run.go b/client/internal/certproof/helper_run.go
index 9345b50f3..cc221669b 100644
--- a/client/internal/certproof/helper_run.go
+++ b/client/internal/certproof/helper_run.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os/exec"
 	"strings"
+	"time"
 
 	log "github.com/sirupsen/logrus"
 
@@ -16,6 +17,13 @@ import (
 const (
 	maxHelperStdout = 1 << 20
 	maxHelperStderr = 4 << 10
+
+	// helperWaitDelay bounds how long Wait keeps reading the helper's output after the
+	// process we launched is gone. Killing that process does not close the pipe its own
+	// children inherited, and on macOS they are the ones doing the work: we launch
+	// launchctl, which launches sudo, which launches the helper. Without this, a helper
+	// stuck on a keychain prompt leaves Wait blocked with no deadline at all.
+	helperWaitDelay = time.Second
 )
 
 var errHelperOutputTooLarge = errors.New("helper output exceeds the size limit")
@@ -34,6 +42,7 @@ func runHelperCmd(cmd *exec.Cmd, req HelperRequest) ([]certposture.Proof, error)
 	cmd.Stdin = bytes.NewReader(payload)
 	cmd.Stdout = stdout
 	cmd.Stderr = stderr
+	cmd.WaitDelay = helperWaitDelay
 
 	if err := cmd.Run(); err != nil {
 		return nil, fmt.Errorf("%w: %s", err, strings.TrimSpace(stderr.String()))
diff --git a/client/internal/certproof/helper_run_test.go b/client/internal/certproof/helper_run_test.go
index be4de9cbf..8a893f903 100644
--- a/client/internal/certproof/helper_run_test.go
+++ b/client/internal/certproof/helper_run_test.go
@@ -8,6 +8,7 @@ import (
 	"os/exec"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -64,6 +65,30 @@ func TestRunHelperCmd_CapsStderrInError(t *testing.T) {
 	assert.True(t, strings.Contains(err.Error(), "exit status 3"), "the exit status is kept: %v", err)
 }
 
+func TestRunHelperCmd_ReturnsWhenAGrandchildHoldsTheOutputPipe(t *testing.T) {
+	req := HelperRequest{Challenges: []HelperChallenge{{Nonce: []byte("asked")}}}
+	resp := HelperResponse{Proofs: []certposture.Proof{{Nonce: []byte("asked"), Signature: []byte("sig")}}}
+
+	// The helper answers and exits, but leaves a background process holding the stdout
+	// it inherited. This is what a wedged `netbird posture cert-proof` behind a keychain
+	// prompt looks like from here: killing the process we launched does not close the
+	// pipe, so the copy out of it never sees EOF.
+	script := printJSON(t, resp) + "; sleep 10 &"
+
+	done := make(chan error, 1)
+	go func() {
+		_, err := runHelperCmd(fakeHelper(t, script), req)
+		done <- err
+	}()
+
+	select {
+	case err := <-done:
+		assert.ErrorIs(t, err, exec.ErrWaitDelay, "the output is incomplete, so the run must fail rather than report proofs")
+	case <-time.After(5 * time.Second):
+		t.Fatal("runHelperCmd never returned while a grandchild held the output pipe, so the collector's busy latch would stay set for the life of the daemon")
+	}
+}
+
 func TestRunHelperCmd_RejectsGarbage(t *testing.T) {
 	req := HelperRequest{Challenges: []HelperChallenge{{Nonce: []byte("asked")}}}