diff --git a/src/eol/utils.test.ts b/src/eol/utils.test.ts
index e6aad79..1ae75ef 100644
--- a/src/eol/utils.test.ts
+++ b/src/eol/utils.test.ts
@@ -6,6 +6,7 @@ import {
   createPurlIdentity,
   canonicalizeVersionFilter,
 } from './utils.ts';
+import { isUnknownReason, UNKNOWN_REASONS } from '../types/eol-scan.ts';
 import type { EolScanComponentMetadata } from '../types/eol-scan.ts';
 
 // These are required for the object but not used to derive the status
@@ -84,6 +85,42 @@ describe('deriveComponentStatus', () => {
     const result = deriveComponentStatus(metadata);
     assert.equal(result, 'OK');
   });
+
+  for (const unknownReason of UNKNOWN_REASONS) {
+    test(`should return UNKNOWN for unknownReason "${unknownReason}"`, () => {
+      const result = deriveComponentStatus({ unknownReason });
+      assert.equal(result, 'UNKNOWN');
+    });
+  }
+
+  test('should return UNKNOWN for an unrecognized unknownReason value', () => {
+    const result = deriveComponentStatus({
+      unknownReason: 'something_else',
+    } as never);
+    assert.equal(result, 'UNKNOWN');
+  });
+});
+
+describe('isUnknownReason', () => {
+  for (const unknownReason of UNKNOWN_REASONS) {
+    test(`returns true for "${unknownReason}"`, () => {
+      assert.equal(isUnknownReason(unknownReason), true);
+    });
+  }
+
+  test('returns false for null', () => {
+    assert.equal(isUnknownReason(null), false);
+  });
+
+  test('returns false for an unrecognized string', () => {
+    assert.equal(isUnknownReason('something_else'), false);
+  });
+
+  test('returns false for non-string garbage', () => {
+    assert.equal(isUnknownReason(42), false);
+    assert.equal(isUnknownReason(undefined), false);
+    assert.equal(isUnknownReason({}), false);
+  });
 });
 
 describe('createPurlIdentity', () => {
diff --git a/src/eol/utils.ts b/src/eol/utils.ts
index aedd571..da27eab 100644
--- a/src/eol/utils.ts
+++ b/src/eol/utils.ts
@@ -1,8 +1,9 @@
 import { PackageURL } from 'packageurl-js';
 import type { CdxBom } from '../types/index.js';
 import type {
+  ComponentMetadata,
   ComponentStatus,
-  EolScanComponentMetadata,
+  UnknownComponentMetadata,
 } from '../types/eol-scan.js';
 
 // Maps non-canonical PURL type tokens to their canonical equivalents.
@@ -243,10 +244,16 @@ export function canonicalizeVersionFilter<
   } as TFilter;
 }
 
+function isUnknownComponentMetadata(
+  metadata: ComponentMetadata,
+): metadata is UnknownComponentMetadata {
+  return 'unknownReason' in metadata && metadata.unknownReason != null;
+}
+
 export function deriveComponentStatus(
-  metadata: EolScanComponentMetadata | null,
+  metadata: ComponentMetadata | null,
 ): ComponentStatus {
-  if (!metadata) {
+  if (!metadata || isUnknownComponentMetadata(metadata)) {
     return 'UNKNOWN';
   }
 
diff --git a/src/index.ts b/src/index.ts
index a7f0557..aa24d41 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -16,6 +16,7 @@ export type {
 } from './eol/utils.js';
 
 export type * from './types/eol-scan.js';
+export { UNKNOWN_REASONS, isUnknownReason } from './types/eol-scan.js';
 export type * from './types/index.js';
 
 export { ComponentScope } from './types/index.js';
diff --git a/src/types/eol-scan.ts b/src/types/eol-scan.ts
index c3144a1..e514f2f 100644
--- a/src/types/eol-scan.ts
+++ b/src/types/eol-scan.ts
@@ -25,6 +25,28 @@ export interface EolScanNextSupportedVersion {
   releasedAt: Date;
 }
 
+export const UNKNOWN_REASONS = [
+  'not_identifiable',
+  'no_listed_versions',
+  'unsupported_ecosystem',
+  'queued',
+] as const;
+export type UnknownReason = (typeof UNKNOWN_REASONS)[number];
+
+export interface UnknownComponentMetadata {
+  unknownReason: UnknownReason;
+}
+
+export type ComponentMetadata =
+  | EolScanComponentMetadata
+  | UnknownComponentMetadata;
+
+export function isUnknownReason(v: unknown): v is UnknownReason {
+  return (
+    typeof v === 'string' && (UNKNOWN_REASONS as readonly string[]).includes(v)
+  );
+}
+
 export interface NesRemediation {
   remediations: {
     purls: { nes: string; oss: string };
@@ -67,7 +89,7 @@ export interface Remediation {
 }
 
 export interface EolScanComponent {
-  metadata: EolScanComponentMetadata | null;
+  metadata: ComponentMetadata | null;
   purl: string;
   nesRemediation?: NesRemediation | null;
   remediations?: Remediation[] | null;