diff --git a/lib/media/media_source_engine.js b/lib/media/media_source_engine.js
index 877c0e37b2..876e302a07 100644
--- a/lib/media/media_source_engine.js
+++ b/lib/media/media_source_engine.js
@@ -1665,6 +1665,7 @@ shaka.media.MediaSourceEngine = class {
     if (shaka.media.Capabilities.isChangeTypeSupported()) {
       if (this.transmuxers_[contentType]) {
         this.transmuxers_[contentType].destroy();
+        delete this.transmuxers_[contentType];
       }
       if (transmuxer) {
         this.transmuxers_[contentType] = transmuxer;
@@ -1867,8 +1868,8 @@ shaka.media.MediaSourceEngine = class {
       }
     }
 
-    const newCodec = MimeUtils.getCodecBase(
-        MimeUtils.getCodecs(newMimeType));
+    const newAllCodecs = MimeUtils.getCodecs(newMimeType);
+    const newCodec = MimeUtils.getCodecBase(newAllCodecs);
     const newBasicType = MimeUtils.getBasicType(newMimeType);
 
     // Current/new codecs base and basic type match then no need to switch
@@ -1876,10 +1877,15 @@ shaka.media.MediaSourceEngine = class {
       return false;
     }
 
-    if (this.config_.codecSwitchingStrategy ===
+    let allowChangeType = true;
+    if (this.needSplitMuxedContent_ || (newAllCodecs.split(',').length &&
+        transmuxer && !this.transmuxers_[contentType])) {
+      allowChangeType = false;
+    }
+
+    if (allowChangeType && this.config_.codecSwitchingStrategy ===
         shaka.config.CodecSwitchingStrategy.SMOOTH &&
-          shaka.media.Capabilities.isChangeTypeSupported() &&
-            !this.needSplitMuxedContent_) {
+          shaka.media.Capabilities.isChangeTypeSupported()) {
       await this.changeType(contentType, newMimeType, transmuxer);
     } else {
       if (transmuxer) {