diff --git a/pc/sdp_offer_answer_unittest.cc b/pc/sdp_offer_answer_unittest.cc
index 72ea4f9f22..03bea2a23e 100644
--- a/pc/sdp_offer_answer_unittest.cc
+++ b/pc/sdp_offer_answer_unittest.cc
@@ -930,4 +930,33 @@ TEST_F(SdpOfferAnswerTest, AllowOnlyOneSsrcGroupPerSemanticAndPrimarySsrc) {
   EXPECT_FALSE(pc->SetLocalDescription(std::move(modified_offer)));
 }
 
+TEST_F(SdpOfferAnswerTest, OfferWithRtxAndNoMsidIsNotRejected) {
+  auto pc = CreatePeerConnection();
+  std::string sdp =
+      "v=0\r\n"
+      "o=- 0 3 IN IP4 127.0.0.1\r\n"
+      "s=-\r\n"
+      "t=0 0\r\n"
+      "a=group:BUNDLE 0\r\n"
+      "a=fingerprint:sha-1 "
+      "4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB\r\n"
+      "a=setup:actpass\r\n"
+      "a=ice-ufrag:ETEn\r\n"
+      "a=ice-pwd:OtSK0WpNtpUjkY4+86js7Z/l\r\n"
+      "m=video 9 UDP/TLS/RTP/SAVPF 96 97\r\n"
+      "c=IN IP4 0.0.0.0\r\n"
+      "a=rtcp-mux\r\n"
+      "a=sendonly\r\n"
+      "a=mid:0\r\n"
+      // "a=msid:stream obsoletetrack\r\n"
+      "a=rtpmap:96 VP8/90000\r\n"
+      "a=rtpmap:97 rtx/90000\r\n"
+      "a=fmtp:97 apt=96\r\n"
+      "a=ssrc-group:FID 1 2\r\n"
+      "a=ssrc:1 cname:test\r\n"
+      "a=ssrc:2 cname:test\r\n";
+  auto offer = CreateSessionDescription(SdpType::kOffer, sdp);
+  EXPECT_TRUE(pc->SetRemoteDescription(std::move(offer)));
+}
+
 }  // namespace webrtc
diff --git a/pc/webrtc_sdp.cc b/pc/webrtc_sdp.cc
index ecba22a85a..71cd18cfb6 100644
--- a/pc/webrtc_sdp.cc
+++ b/pc/webrtc_sdp.cc
@@ -706,7 +706,7 @@ void CreateTracksFromSsrcInfos(const SsrcInfoVec& ssrc_infos,
                                absl::string_view msid_track_id,
                                StreamParamsVec* tracks,
                                int msid_signaling) {
-  RTC_DCHECK(tracks != NULL);
+  RTC_DCHECK(tracks);
   for (const SsrcInfo& ssrc_info : ssrc_infos) {
     // According to https://tools.ietf.org/html/rfc5576#section-6.1, the CNAME
     // attribute is mandatory, but we relax that restriction.
@@ -726,16 +726,9 @@ void CreateTracksFromSsrcInfos(const SsrcInfoVec& ssrc_infos,
       track_id = ssrc_info.track_id;
     } else {
       // Since no media streams isn't supported with older SDP signaling, we
-      // use a default a stream id.
+      // use a default stream id.
       stream_ids.push_back(kDefaultMsid);
     }
-    // If a track ID wasn't populated from the SSRC attributes OR the
-    // msid attribute, use default/random values.
-    if (track_id.empty()) {
-      // TODO(ronghuawu): What should we do if the track id doesn't appear?
-      // Create random string (which will be used as track label later)?
-      track_id = rtc::CreateRandomString(8);
-    }
 
     auto track_it = absl::c_find_if(
         *tracks,
@@ -751,6 +744,14 @@ void CreateTracksFromSsrcInfos(const SsrcInfoVec& ssrc_infos,
     track.set_stream_ids(stream_ids);
     track.id = track_id;
   }
+  for (StreamParams& stream : *tracks) {
+    // If a track ID wasn't populated from the SSRC attributes OR the
+    // msid attribute, use default/random values. This happens after
+    // deduplication.
+    if (stream.id.empty()) {
+      stream.id = rtc::CreateRandomString(8);
+    }
+  }
 }
 
 void GetMediaStreamIds(const ContentInfo* content,