--- a/media/webrtc/signaling/src/jsep/JsepTrack.cpp
+++ b/media/webrtc/signaling/src/jsep/JsepTrack.cpp
@@ -461,17 +461,25 @@ JsepTrack::Negotiate(const SdpMediaSecti
 
   UniquePtr<JsepTrackNegotiatedDetails> negotiatedDetails =
       MakeUnique<JsepTrackNegotiatedDetails>();
 
   CreateEncodings(remote, negotiatedCodecs.values, negotiatedDetails.get());
 
   if (answer.GetAttributeList().HasAttribute(SdpAttribute::kExtmapAttribute)) {
     for (auto& extmapAttr : answer.GetAttributeList().GetExtmap().mExtmaps) {
-      negotiatedDetails->mExtmap[extmapAttr.extensionname] = extmapAttr;
+      SdpDirectionAttribute::Direction direction = extmapAttr.direction;
+      if (&remote == &answer) {
+        // Answer is remote, we need to flip this.
+        direction = ~direction;
+      }
+
+      if (direction & mDirection) {
+        negotiatedDetails->mExtmap[extmapAttr.extensionname] = extmapAttr;
+      }
     }
   }
 
   if (mDirection == sdp::kRecv) {
     mSsrcs.clear();
     if (remote.GetAttributeList().HasAttribute(SdpAttribute::kSsrcAttribute)) {
       for (auto& ssrcAttr : remote.GetAttributeList().GetSsrc().mSsrcs) {
         AddSsrc(ssrcAttr.ssrc);