@@ -435,45 +435,51 @@ function deriveKeyImpl(
 }
 
 function exportKeySpki(key) {
+  let exporter;
   switch (getCryptoKeyAlgorithm(key).name) {
     case 'RSASSA-PKCS1-v1_5':
       // Fall through
     case 'RSA-PSS':
       // Fall through
     case 'RSA-OAEP':
-      return require('internal/crypto/rsa')
-        .rsaExportKey(key, kWebCryptoKeyFormatSPKI);
+      exporter = require('internal/crypto/rsa').rsaExportKey;
+      break;
     case 'ECDSA':
       // Fall through
     case 'ECDH':
-      return require('internal/crypto/ec')
-        .ecExportKey(key, kWebCryptoKeyFormatSPKI);
+      exporter = require('internal/crypto/ec').ecExportKey;
+      break;
     case 'Ed25519':
       // Fall through
     case 'Ed448':
       // Fall through
     case 'X25519':
       // Fall through
     case 'X448':
-      return require('internal/crypto/cfrg')
-        .cfrgExportKey(key, kWebCryptoKeyFormatSPKI);
+      exporter = require('internal/crypto/cfrg').cfrgExportKey;
+      break;
     case 'ML-DSA-44':
       // Fall through
     case 'ML-DSA-65':
       // Fall through
     case 'ML-DSA-87':
-      return require('internal/crypto/ml_dsa')
-        .mlDsaExportKey(key, kWebCryptoKeyFormatSPKI);
+      exporter = require('internal/crypto/ml_dsa').mlDsaExportKey;
+      break;
     case 'ML-KEM-512':
       // Fall through
     case 'ML-KEM-768':
       // Fall through
     case 'ML-KEM-1024':
-      return require('internal/crypto/ml_kem')
-        .mlKemExportKey(key, kWebCryptoKeyFormatSPKI);
+      exporter = require('internal/crypto/ml_kem').mlKemExportKey;
+      break;
     default:
       return undefined;
   }
+
+  if (getCryptoKeyType(key) !== 'public')
+    throw lazyDOMException('Key must be a public key', 'InvalidAccessError');
+
+  return exporter(key, kWebCryptoKeyFormatSPKI);
 }
 
 function exportKeyPkcs8(key) {
@@ -720,9 +726,7 @@ function exportKeySync(format, key) {
   let result;
   switch (format) {
     case 'spki': {
-      if (type === 'public') {
-        result = exportKeySpki(key);
-      }
+      result = exportKeySpki(key);
       break;
     }
     case 'pkcs8': {
 
@@ -162,6 +162,12 @@ async function testImportPkcs8(
     assert.strictEqual(
       Buffer.from(pkcs8).toString('hex'),
       keyData[namedCurve].pkcs8.toString('hex'));
+
+    await assert.rejects(
+      subtle.exportKey('spki', key), {
+        message: 'Key must be a public key',
+        name: 'InvalidAccessError',
+      });
   } else {
     await assert.rejects(
       subtle.exportKey('pkcs8', key), {
 
@@ -455,7 +455,7 @@ async function testNonByteLengthWrapUnwrap({
 // Test that wrapKey/unwrapKey validate the wrapping/unwrapping key's
 // algorithm and usage before proceeding.
 // Spec: https://w3c.github.io/webcrypto/#SubtleCrypto-method-wrapKey
-// Steps 9-10 (wrapping key checks) must precede step 12 (exportKey).
+// Steps 9-10 (wrapping key checks) must precede step 13 (export operation).
 (async function() {
   const hmacKey = await subtle.generateKey(
     { name: 'HMAC', hash: 'SHA-256' },
@@ -500,7 +500,7 @@ async function testNonByteLengthWrapUnwrap({
     });
 
   // Correct wrapping key algorithm and usage results in the expected
-  // exportKey error (not the wrapping key validation error).
+  // export operation error (not the wrapping key validation error).
   const wrapKey = await subtle.generateKey(
     { name: 'AES-GCM', length: 128 },
     true,
@@ -512,8 +512,8 @@ async function testNonByteLengthWrapUnwrap({
       name: 'AES-GCM',
       iv: new Uint8Array(12),
     }), {
-      // exportKey('spki', privateKey) throws NotSupportedError
-      name: 'NotSupportedError',
+      message: 'Key must be a public key',
+      name: 'InvalidAccessError',
     });
 
   // --- unwrapKey validation tests ---