diff --git a/internal/storage/storage.go b/internal/storage/storage.go
index 3ccb6b6..ec69e3a 100644
--- a/internal/storage/storage.go
+++ b/internal/storage/storage.go
@@ -178,6 +178,8 @@ type Smart struct {
 	NVMe         *NVMeLog `json:"nvme,omitempty"`
 	SelfTest     string   `json:"self_test,omitempty"`
 	SelfTestPct  int      `json:"self_test_remaining,omitempty"`
+	SelfTestOK   bool     `json:"self_test_supported"`
+	SelfTestNote string   `json:"self_test_note,omitempty"`
 	Warnings     []string `json:"warnings"`
 	Error        string   `json:"error,omitempty"`
 	FetchedAt    int64    `json:"fetched_at"`
@@ -381,6 +383,30 @@ func (m *Manager) Smart(ctx context.Context, dev string, force bool) Smart {
 			s.Warnings = append(s.Warnings, "endurance "+strconv.Itoa(l.PercentageUsed)+"% used")
 		}
 	}
+	// Can this drive run self-tests from here? ATA says so outright; NVMe drives prove it
+	// by exposing the self-test log, and some (WD SN580 among them) advertise the command
+	// but reject the log page, which makes the whole feature unusable.
+	if d, ok := raw["ata_smart_data"].(map[string]any); ok {
+		if caps, ok := d["capabilities"].(map[string]any); ok {
+			s.SelfTestOK = caps["self_tests_supported"] == true
+			if !s.SelfTestOK {
+				s.SelfTestNote = "drive reports no self-test support"
+			}
+		}
+	}
+	if _, ok := raw["nvme_self_test_log"]; ok {
+		s.SelfTestOK = true
+	} else if s.NVMe != nil {
+		s.SelfTestNote = "this drive's firmware doesn't expose the NVMe self-test log, so tests can't be run or read from here"
+	}
+	if msgs, ok := raw["smartctl"].(map[string]any); ok {
+		for _, mm := range asList(msgs["messages"]) {
+			if strings.Contains(asString(mm["string"]), "Self-test Log failed") {
+				s.SelfTestOK = false
+				s.SelfTestNote = "firmware rejects the self-test log page (" + asString(mm["string"]) + ")"
+			}
+		}
+	}
 	if d, ok := raw["ata_smart_data"].(map[string]any); ok {
 		if st, ok := d["self_test"].(map[string]any); ok {
 			if ss, ok := st["status"].(map[string]any); ok {
@@ -438,6 +464,9 @@ func (m *Manager) SelfTest(ctx context.Context, dev, kind string) error {
 	if !m.smartctl {
 		return errors.New("smartctl is not installed")
 	}
+	if sm := m.Smart(ctx, dev, false); sm.Supported && !sm.SelfTestOK {
+		return errors.New("self-tests aren't available on this drive: " + sm.SelfTestNote)
+	}
 	out, code, err := m.run(ctx, "smartctl", "-t", kind, "/dev/"+dev)
 	if err != nil {
 		return err
diff --git a/web/src/Disks.tsx b/web/src/Disks.tsx
index 98bd664..2b426d8 100644
--- a/web/src/Disks.tsx
+++ b/web/src/Disks.tsx
@@ -62,10 +62,11 @@ function SmartPanel({ dev, rotational }: { dev: string; rotational: boolean }) {
           </tbody>
         </table>
       )}
-      <div className="svc-actions">
+      {!s.self_test_supported && <div className="muted small">Self-tests: {s.self_test_note || 'not available on this drive'}.</div>}
+      {s.self_test_supported && <div className="svc-actions">
         <Btn className="btn" confirm={`Start a short self-test on ${dev}?`} onClick={async () => { if (await api.smartTest(dev, 'short').then(() => true, (e) => { toast(String(e.message ?? e), 'err'); return false })) { toast('short test started'); load(true) } }}>Short test</Btn>
         <Btn className="btn" confirm={`Start a long self-test on ${dev}? ${rotational ? 'This can take hours on a spinning disk.' : ''}`} onClick={async () => { if (await api.smartTest(dev, 'long').then(() => true, (e) => { toast(String(e.message ?? e), 'err'); return false })) { toast('long test started'); load(true) } }}>Long test</Btn>
-      </div>
+      </div>}
     </div>
   )
 }
diff --git a/web/src/api.ts b/web/src/api.ts
index a335338..6dab538 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -83,7 +83,7 @@ export interface UpdatesStatus { manager: string; can_upgrade: boolean; packages
 export interface StoragePart { name: string; type: string; fstype?: string; mount?: string; label?: string; size: number; used?: number; fs_size?: number }
 export interface StorageDevice { name: string; kind: string; model?: string; vendor?: string; serial?: string; tran?: string; size: number; rotational: boolean; removable: boolean; temp?: number; parts: StoragePart[] }
 export interface SmartAttr { id: number; name: string; value: number; worst: number; thresh: number; raw: string; failed?: string; warn: boolean }
-export interface SmartInfo { device: string; available: boolean; supported: boolean; standby: boolean; passed: boolean | null; temp: number; power_on_hours: number; power_cycles: number; model?: string; serial?: string; firmware?: string; attrs: SmartAttr[]; nvme?: { critical_warning: number; percentage_used: number; available_spare: number; spare_threshold: number; media_errors: number; error_log_entries: number; data_read_bytes: number; data_written_bytes: number; unsafe_shutdowns: number }; self_test?: string; self_test_remaining?: number; warnings: string[]; error?: string; fetched_at: number }
+export interface SmartInfo { device: string; available: boolean; supported: boolean; standby: boolean; passed: boolean | null; temp: number; power_on_hours: number; power_cycles: number; model?: string; serial?: string; firmware?: string; attrs: SmartAttr[]; nvme?: { critical_warning: number; percentage_used: number; available_spare: number; spare_threshold: number; media_errors: number; error_log_entries: number; data_read_bytes: number; data_written_bytes: number; unsafe_shutdowns: number }; self_test?: string; self_test_remaining?: number; self_test_supported: boolean; self_test_note?: string; warnings: string[]; error?: string; fetched_at: number }
 export interface ZFSSnapshot { name: string; used: number; created: number }
 export interface ZFSInfo { available: boolean; message?: string; pools: { name: string; size: number; alloc: number; free: number; frag: number; cap: number; health: string; dedup: string; scan?: string; errors?: string; config?: string }[]; datasets: { name: string; type: string; used: number; avail: number; refer: number; used_by_snapshots: number; mount?: string; compressratio: string; snapshots: number }[] }