diff --git a/lib/media/drm_engine.js b/lib/media/drm_engine.js
index f90e2f48e8..794d426a72 100644
--- a/lib/media/drm_engine.js
+++ b/lib/media/drm_engine.js
@@ -934,14 +934,16 @@ shaka.media.DrmEngine = class {
           'Got MediaKeySystemAccess with configuration',
           realConfig);
 
+      const keySystem =
+          this.config_.keySystemsMapping[mediaKeySystemAccess.keySystem] ||
+          mediaKeySystemAccess.keySystem;
+
       if (variants.length) {
         this.currentDrmInfo_ = this.createDrmInfoByInfos_(
-            mediaKeySystemAccess.keySystem,
-            drmInfosByKeySystem.get(mediaKeySystemAccess.keySystem));
+            keySystem, drmInfosByKeySystem.get(keySystem));
       } else {
         this.currentDrmInfo_ = shaka.media.DrmEngine.createDrmInfoByConfigs_(
-            mediaKeySystemAccess.keySystem,
-            configsByKeySystem.get(mediaKeySystemAccess.keySystem));
+            keySystem, configsByKeySystem.get(keySystem));
       }
       if (!this.currentDrmInfo_.licenseServerUri) {
         throw new shaka.util.Error(
@@ -1056,8 +1058,12 @@ shaka.media.DrmEngine = class {
           if (!decodingInfo.supported || !decodingInfo.keySystemAccess) {
             continue;
           }
-          const drmInfos =
-              drmInfosByKeySystem.get(decodingInfo.keySystemAccess.keySystem);
+          const originalKeySystem = decodingInfo.keySystemAccess.keySystem;
+          let drmInfos = drmInfosByKeySystem.get(originalKeySystem);
+          if (!drmInfos && this.config_.keySystemsMapping[originalKeySystem]) {
+            drmInfos = drmInfosByKeySystem.get(
+                this.config_.keySystemsMapping[originalKeySystem]);
+          }
           for (const info of drmInfos) {
             if (!!info.licenseServerUri == shouldHaveLicenseServer) {
               return decodingInfo.keySystemAccess;
diff --git a/lib/media/manifest_filterer.js b/lib/media/manifest_filterer.js
index 30ecbd13a5..e0601fe5e2 100644
--- a/lib/media/manifest_filterer.js
+++ b/lib/media/manifest_filterer.js
@@ -50,7 +50,8 @@ shaka.media.ManifestFilterer = class {
   async filterManifest(manifest) {
     goog.asserts.assert(manifest, 'Manifest should exist!');
     await shaka.util.StreamUtils.filterManifest(this.drmEngine_, manifest,
-        this.config_.drm.preferredKeySystems);
+        this.config_.drm.preferredKeySystems,
+        this.config_.drm.keySystemsMapping);
     if (!this.config_.streaming.dontChooseCodecs) {
       shaka.util.StreamUtils.chooseCodecsAndFilterManifest(
           manifest,
diff --git a/lib/offline/storage.js b/lib/offline/storage.js
index e73a30822e..212a38a300 100644
--- a/lib/offline/storage.js
+++ b/lib/offline/storage.js
@@ -702,7 +702,7 @@ shaka.offline.Storage = class {
     // to play later (no point storing something we can't play).
     await shaka.util.StreamUtils.filterManifestByMediaCapabilities(
         drmEngine, manifest, config.offline.usePersistentLicense,
-        config.drm.preferredKeySystems);
+        config.drm.preferredKeySystems, config.drm.keySystemsMapping);
 
     // Gather all tracks.
     const allTracks = [];
diff --git a/lib/util/stream_utils.js b/lib/util/stream_utils.js
index 1517ac5112..4bdcbd1e0b 100644
--- a/lib/util/stream_utils.js
+++ b/lib/util/stream_utils.js
@@ -393,11 +393,13 @@ shaka.util.StreamUtils = class {
    * @param {shaka.media.DrmEngine} drmEngine
    * @param {shaka.extern.Manifest} manifest
    * @param {!Array<string>=} preferredKeySystems
+   * @param {!Object.<string, string>=} keySystemsMapping
    */
-  static async filterManifest(drmEngine, manifest, preferredKeySystems = []) {
+  static async filterManifest(drmEngine, manifest, preferredKeySystems = [],
+      keySystemsMapping = {}) {
     await shaka.util.StreamUtils.filterManifestByMediaCapabilities(
         drmEngine, manifest, manifest.offlineSessionIds.length > 0,
-        preferredKeySystems);
+        preferredKeySystems, keySystemsMapping);
     shaka.util.StreamUtils.filterTextStreams_(manifest);
     await shaka.util.StreamUtils.filterImageStreams_(manifest);
   }
@@ -411,9 +413,11 @@ shaka.util.StreamUtils = class {
    * @param {shaka.extern.Manifest} manifest
    * @param {boolean} usePersistentLicenses
    * @param {!Array<string>} preferredKeySystems
+   * @param {!Object.<string, string>} keySystemsMapping
    */
   static async filterManifestByMediaCapabilities(
-      drmEngine, manifest, usePersistentLicenses, preferredKeySystems) {
+      drmEngine, manifest, usePersistentLicenses, preferredKeySystems,
+      keySystemsMapping) {
     goog.asserts.assert(navigator.mediaCapabilities,
         'MediaCapabilities should be valid.');
 
@@ -435,7 +439,8 @@ shaka.util.StreamUtils = class {
     const StreamUtils = shaka.util.StreamUtils;
 
     manifest.variants = manifest.variants.filter((variant) => {
-      const supported = StreamUtils.checkVariantSupported_(variant, keySystem);
+      const supported = StreamUtils.checkVariantSupported_(
+          variant, keySystem, keySystemsMapping);
       // Filter out all unsupported variants.
       if (!supported) {
         shaka.log.debug('Dropping variant - not compatible with platform',
@@ -485,10 +490,11 @@ shaka.util.StreamUtils = class {
   /**
    * @param {!shaka.extern.Variant} variant
    * @param {?string} keySystem
+   * @param {!Object.<string, string>} keySystemsMapping
    * @return {boolean}
    * @private
    */
-  static checkVariantSupported_(variant, keySystem) {
+  static checkVariantSupported_(variant, keySystem, keySystemsMapping) {
     const variantSupported = variant.decodingInfos.some((decodingInfo) => {
       if (!decodingInfo.supported) {
         return false;
@@ -496,7 +502,10 @@ shaka.util.StreamUtils = class {
       if (keySystem) {
         const keySystemAccess = decodingInfo.keySystemAccess;
         if (keySystemAccess) {
-          if (keySystemAccess.keySystem != keySystem) {
+          const currentKeySystem =
+              keySystemsMapping[keySystemAccess.keySystem] ||
+              keySystemAccess.keySystem;
+          if (currentKeySystem != keySystem) {
             return false;
           }
         }