diff --git a/spinifex/daemon/cluster_ready_test.go b/spinifex/daemon/cluster_ready_test.go
index 4bf28d932..9762d6554 100644
--- a/spinifex/daemon/cluster_ready_test.go
+++ b/spinifex/daemon/cluster_ready_test.go
@@ -92,7 +92,10 @@ func TestWaitForClusterReady_PredastoreBecomesReady(t *testing.T) {
 	require.NoError(t, err)
 
 	d := &Daemon{
-		config:   &config.Config{Predastore: config.PredastoreConfig{Host: closedPort(t)}},
+		config: &config.Config{
+			Predastore: config.PredastoreConfig{Host: closedPort(t)},
+			NATS:       config.NATSConfig{CACert: writeServerCA(t, srv)},
+		},
 		natsConn: nc,
 	}
 
diff --git a/spinifex/daemon/daemon.go b/spinifex/daemon/daemon.go
index 5794427b6..58d7f290a 100644
--- a/spinifex/daemon/daemon.go
+++ b/spinifex/daemon/daemon.go
@@ -2574,15 +2574,6 @@ func (d *Daemon) checkViperblockReady() bool {
 	return err == nil
 }
 
-// predastoreReadinessClient is hoisted to package scope so the 2s readiness
-// poll loop doesn't build a fresh transport every call. Verification is off
-// because the probe authenticates nothing and reads no data.
-var predastoreReadinessClient = &http.Client{
-	Transport: &http.Transport{
-		TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, //nolint:gosec // readiness probe only, no data exchanged
-	},
-}
-
 // checkPredastoreReady reports whether predastore is serving HTTPS, not just
 // listening. Any response counts as ready, including the 401/403 an S3
 // endpoint returns for this deliberately unsigned request.
@@ -2595,11 +2586,18 @@ func (d *Daemon) checkPredastoreReady() bool {
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()
 
+	rootCAs, err := loadClusterTrustRoot(d)
+	if err != nil {
+		slog.Warn("predastore readiness probe: could not load cluster CA", "err", err)
+		return false
+	}
+	client := &http.Client{Transport: &http.Transport{TLSClientConfig: &tls.Config{RootCAs: rootCAs}}}
+	defer client.CloseIdleConnections()
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://"+host+"/", nil)
 	if err != nil {
 		return false
 	}
-	resp, err := predastoreReadinessClient.Do(req)
+	resp, err := client.Do(req)
 	if err != nil {
 		return false
 	}
diff --git a/spinifex/daemon/health.go b/spinifex/daemon/health.go
index 82540a9b5..677c6b4a9 100644
--- a/spinifex/daemon/health.go
+++ b/spinifex/daemon/health.go
@@ -165,7 +165,7 @@ func computePredastoreHealth(ctx context.Context, d *Daemon) string {
 		return probeLocalGate(ctx, d, cfg, hostID)
 	}
 
-	rootCAs, err := loadPredastoreTrustRoot(d)
+	rootCAs, err := loadClusterTrustRoot(d)
 	if err != nil {
 		slog.Warn("predastore health probe: could not load cluster CA", "err", err)
 		return predastoreHealthUnreachable
@@ -332,11 +332,11 @@ func predastoreConfigPath(daemonConfigPath string) string {
 	return filepath.Join(filepath.Dir(daemonConfigPath), "predastore", "predastore.toml")
 }
 
-// loadPredastoreTrustRoot returns the cluster CA pool predastore's meta
-// replicas are issued from — the same CA (d.config.NATS.CACert, conventionally
-// /etc/spinifex/ca.pem) the daemon already trusts NATS peers with.
-func loadPredastoreTrustRoot(d *Daemon) (*x509.CertPool, error) {
-	if d.config.NATS.CACert == "" {
+// loadClusterTrustRoot returns the cluster CA pool (d.config.NATS.CACert,
+// conventionally /etc/spinifex/ca.pem) that issues every node's server cert:
+// daemon peers, predastore replicas and NATS alike.
+func loadClusterTrustRoot(d *Daemon) (*x509.CertPool, error) {
+	if d.config == nil || d.config.NATS.CACert == "" {
 		return nil, fmt.Errorf("cluster CA not configured (nats.cacert)")
 	}
 	return utils.LoadCertPool(d.config.NATS.CACert)
diff --git a/spinifex/daemon/peer_health.go b/spinifex/daemon/peer_health.go
index 04c3d0006..27697b0c1 100644
--- a/spinifex/daemon/peer_health.go
+++ b/spinifex/daemon/peer_health.go
@@ -55,10 +55,17 @@ func (d *Daemon) monitorPeerReachability() {
 		return
 	}
 
+	// Without the CA every probe would fail, flipping the node to partitioned;
+	// leave peersReachable at its initial true instead.
+	rootCAs, err := loadClusterTrustRoot(d)
+	if err != nil {
+		slog.Error("peer reachability probe disabled: could not load cluster CA", "err", err)
+		return
+	}
 	client := &http.Client{
 		Timeout: peerProbeTimeout,
 		Transport: &http.Transport{
-			TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, //nolint:gosec // self-signed per-node certs (matches harness DaemonClient)
+			TLSClientConfig: &tls.Config{RootCAs: rootCAs},
 		},
 	}
 	defer client.CloseIdleConnections()
diff --git a/spinifex/daemon/peer_health_test.go b/spinifex/daemon/peer_health_test.go
index 5d598d1cb..bc7aba433 100644
--- a/spinifex/daemon/peer_health_test.go
+++ b/spinifex/daemon/peer_health_test.go
@@ -2,11 +2,20 @@ package daemon
 
 import (
 	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
 	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"math/big"
 	"net"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"os"
+	"path/filepath"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -20,8 +29,9 @@ import (
 // /health responses, returning the cluster config the daemon-under-test should
 // see plus a handle to flip each peer up or down at runtime.
 type peerHealthFixture struct {
-	peers []*peerStub
-	cfg   *config.ClusterConfig
+	peers  []*peerStub
+	cfg    *config.ClusterConfig
+	caPath string
 }
 
 type peerStub struct {
@@ -61,6 +71,7 @@ func newPeerHealthFixture(t *testing.T, peerCount int) *peerHealthFixture {
 			Daemon:      config.DaemonConfig{Host: "0.0.0.0:" + port},
 		}
 		f.peers = append(f.peers, stub)
+		f.caPath = writeServerCA(t, stub.srv)
 	}
 	f.cfg = &config.ClusterConfig{Node: "node-self", Nodes: nodes}
 	return f
@@ -76,6 +87,40 @@ func daemonForPeerHealth(t *testing.T, cfg *config.ClusterConfig) (*Daemon, cont
 	return d, cancel
 }
 
+// writeServerCA writes srv's self-signed cert as a PEM CA file, standing in for
+// the cluster CA. Every httptest TLS server shares that one cert.
+func writeServerCA(t *testing.T, srv *httptest.Server) string {
+	t.Helper()
+	return writePEMCert(t, srv.Certificate().Raw)
+}
+
+// writeUntrustedCA writes a freshly generated self-signed CA that signed none
+// of the httptest servers' certs.
+func writeUntrustedCA(t *testing.T) string {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	tmpl := &x509.Certificate{
+		SerialNumber:          big.NewInt(1),
+		Subject:               pkix.Name{CommonName: "untrusted test CA"},
+		NotBefore:             time.Now().Add(-time.Hour),
+		NotAfter:              time.Now().Add(time.Hour),
+		IsCA:                  true,
+		BasicConstraintsValid: true,
+		KeyUsage:              x509.KeyUsageCertSign,
+	}
+	der, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
+	require.NoError(t, err)
+	return writePEMCert(t, der)
+}
+
+func writePEMCert(t *testing.T, der []byte) string {
+	t.Helper()
+	path := filepath.Join(t.TempDir(), "ca.pem")
+	require.NoError(t, os.WriteFile(path, pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der}), 0o600))
+	return path
+}
+
 func TestPeerCount_SingleNode(t *testing.T) {
 	cfg := &config.ClusterConfig{
 		Node:  "only",
@@ -194,6 +239,7 @@ func TestMonitorPeerReachability_EndToEnd(t *testing.T) {
 	}
 	f := newPeerHealthFixture(t, 2)
 	d, cancel := daemonForPeerHealth(t, f.cfg)
+	d.config = &config.Config{NATS: config.NATSConfig{CACert: f.caPath}}
 
 	for _, p := range f.peers {
 		p.setHealthy(false)
@@ -211,3 +257,47 @@ func TestMonitorPeerReachability_EndToEnd(t *testing.T) {
 		peerProbeInterval+peerProbeTimeout+time.Second, 50*time.Millisecond,
 		"peersReachable should flip true when any peer comes back")
 }
+
+// TestMonitorPeerReachability_UntrustedPeerCert asserts a peer whose cert the
+// cluster CA did not sign counts as unreachable, even while serving 200.
+func TestMonitorPeerReachability_UntrustedPeerCert(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping ticker-driven peer probe test in short mode")
+	}
+	f := newPeerHealthFixture(t, 1)
+	d, cancel := daemonForPeerHealth(t, f.cfg)
+	d.config = &config.Config{NATS: config.NATSConfig{CACert: writeUntrustedCA(t)}}
+	d.peersReachable.Store(true)
+
+	go d.monitorPeerReachability()
+	defer cancel()
+
+	require.Eventually(t, func() bool { return !d.peersReachable.Load() },
+		peerProbeTimeout+time.Second, 50*time.Millisecond,
+		"a peer presenting an untrusted cert must not count as reachable")
+}
+
+// TestMonitorPeerReachability_NoCAKeepsPeersReachable asserts a node that
+// cannot load the cluster CA stops probing rather than declaring every peer
+// unreachable and dropping out of cluster mode.
+func TestMonitorPeerReachability_NoCAKeepsPeersReachable(t *testing.T) {
+	f := newPeerHealthFixture(t, 2)
+	for _, p := range f.peers {
+		p.setHealthy(false)
+	}
+	d, _ := daemonForPeerHealth(t, f.cfg)
+	d.config = &config.Config{}
+	d.peersReachable.Store(true)
+
+	done := make(chan struct{})
+	go func() {
+		d.monitorPeerReachability()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("monitorPeerReachability kept running without a cluster CA")
+	}
+	assert.True(t, d.peersReachable.Load())
+}
diff --git a/spinifex/daemon/predastore_ready_test.go b/spinifex/daemon/predastore_ready_test.go
index 2a6c9cb38..80f08092d 100644
--- a/spinifex/daemon/predastore_ready_test.go
+++ b/spinifex/daemon/predastore_ready_test.go
@@ -26,10 +26,46 @@ func TestCheckPredastoreReady_HTTPSServing(t *testing.T) {
 	u, err := url.Parse(srv.URL)
 	require.NoError(t, err)
 
-	d := &Daemon{config: &config.Config{Predastore: config.PredastoreConfig{Host: u.Host}}}
+	d := &Daemon{config: &config.Config{
+		Predastore: config.PredastoreConfig{Host: u.Host},
+		NATS:       config.NATSConfig{CACert: writeServerCA(t, srv)},
+	}}
 	assert.True(t, d.checkPredastoreReady())
 }
 
+// TestCheckPredastoreReady_UntrustedCert asserts an endpoint whose cert the
+// cluster CA did not sign is not ready, even though it answers HTTPS.
+func TestCheckPredastoreReady_UntrustedCert(t *testing.T) {
+	srv := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusForbidden)
+	}))
+	t.Cleanup(srv.Close)
+
+	u, err := url.Parse(srv.URL)
+	require.NoError(t, err)
+
+	d := &Daemon{config: &config.Config{
+		Predastore: config.PredastoreConfig{Host: u.Host},
+		NATS:       config.NATSConfig{CACert: writeUntrustedCA(t)},
+	}}
+	assert.False(t, d.checkPredastoreReady())
+}
+
+// TestCheckPredastoreReady_NoClusterCA asserts a node without a configured
+// cluster CA fails closed instead of probing unverified.
+func TestCheckPredastoreReady_NoClusterCA(t *testing.T) {
+	srv := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusForbidden)
+	}))
+	t.Cleanup(srv.Close)
+
+	u, err := url.Parse(srv.URL)
+	require.NoError(t, err)
+
+	d := &Daemon{config: &config.Config{Predastore: config.PredastoreConfig{Host: u.Host}}}
+	assert.False(t, d.checkPredastoreReady())
+}
+
 // TestCheckPredastoreReady_ClosedPort asserts a port nothing is listening on
 // is reported not-ready, rather than panicking or failing open.
 func TestCheckPredastoreReady_ClosedPort(t *testing.T) {