diff --git a/lib/media/drm_engine.js b/lib/media/drm_engine.js
index fb51e9487..4ceed9232 100644
--- a/lib/media/drm_engine.js
+++ b/lib/media/drm_engine.js
@@ -698,7 +698,7 @@ shaka.media.DrmEngine = class {
     // Create a config entry for each key system.
     for (const info of allDrmInfo) {
       const config = {
-        // Ignore initDataTypes.
+        initDataTypes: ['cenc'],
         audioCapabilities: [],
         videoCapabilities: [],
         distinctiveIdentifier: 'optional',
@@ -749,6 +749,13 @@ shaka.media.DrmEngine = class {
           // MediaKeySystemConfiguration
           config['drmInfos'].push(info);
 
+          if (info.initData && info.initData.length) {
+            config.initDataTypes = [
+              ...new Set(
+                  info.initData.map((initData) => initData.initDataType)
+              ),
+            ];
+          }
           if (info.distinctiveIdentifierRequired) {
             config.distinctiveIdentifier = 'required';
           }
@@ -1544,6 +1551,7 @@ shaka.media.DrmEngine = class {
     ];
 
     const basicConfig = {
+      initDataTypes: ['cenc'],
       videoCapabilities: basicVideoCapabilities,
     };
     const offlineConfig = {
diff --git a/lib/polyfill/patchedmediakeys_apple.js b/lib/polyfill/patchedmediakeys_apple.js
index 4e119d9be..4fe5e0076 100644
--- a/lib/polyfill/patchedmediakeys_apple.js
+++ b/lib/polyfill/patchedmediakeys_apple.js
@@ -15,6 +15,7 @@ goog.require('shaka.util.EventManager');
 goog.require('shaka.util.FakeEvent');
 goog.require('shaka.util.FakeEventTarget');
 goog.require('shaka.util.MediaReadyState');
+goog.require('shaka.util.Platform');
 goog.require('shaka.util.PublicPromise');
 goog.require('shaka.util.StringUtils');
 
@@ -33,15 +34,15 @@ shaka.polyfill.PatchedMediaKeysApple = class {
       return;
     }
 
-    // TODO: Prefer unprefixed EME once we know how to use it.
-    // See: https://bugs.webkit.org/show_bug.cgi?id=197433
-    /*
+    // Only tested in Safari 14.
+    const safariVersion = shaka.util.Platform.safariVersion();
     if (navigator.requestMediaKeySystemAccess &&
-        MediaKeySystemAccess.prototype.getConfiguration) {
-      // Prefixed EME is preferable.
+        // eslint-disable-next-line no-restricted-syntax
+        MediaKeySystemAccess.prototype.getConfiguration &&
+        safariVersion && safariVersion >= 14) {
+      // Unprefixed EME is preferable.
       return;
     }
-    */
 
     shaka.log.info('Using Apple-prefixed EME');