diff --git a/pc/BUILD.gn b/pc/BUILD.gn
index a913f42..48c864b1 100644
--- a/pc/BUILD.gn
+++ b/pc/BUILD.gn
@@ -208,6 +208,7 @@
     "../logging:rtc_event_log_impl_output",
     "../media:rtc_data",
     "../media:rtc_media_base",
+    "../modules/rtp_rtcp:rtp_rtcp_format",
     "../p2p:rtc_p2p",
     "../rtc_base",
     "../rtc_base:checks",
diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index 656e21d..6e05d54 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -24,11 +24,14 @@
 #include "api/jsep_session_description.h"
 #include "api/media_stream_proxy.h"
 #include "api/media_stream_track_proxy.h"
+#include "api/rtc_error.h"
+#include "api/rtp_parameters.h"
 #include "api/uma_metrics.h"
 #include "call/call.h"
 #include "logging/rtc_event_log/ice_logger.h"
 #include "logging/rtc_event_log/output/rtc_event_log_output_file.h"
 #include "logging/rtc_event_log/rtc_event_log.h"
+#include "media/base/rid_description.h"
 #include "media/sctp/sctp_transport.h"
 #include "pc/audio_rtp_receiver.h"
 #include "pc/audio_track.h"
@@ -1547,6 +1550,14 @@
         "RIDs must be provided for either all or none of the send encodings.");
   }
 
+  if (num_rids > 0 && absl::c_any_of(init.send_encodings,
+                                     [](const RtpEncodingParameters& encoding) {
+                                       return !IsLegalRsidName(encoding.rid);
+                                     })) {
+    LOG_AND_RETURN_ERROR(RTCErrorType::INVALID_PARAMETER,
+                         "Invalid RID value provided.");
+  }
+
   if (absl::c_any_of(init.send_encodings,
                      [](const RtpEncodingParameters& encoding) {
                        return encoding.ssrc.has_value();
diff --git a/pc/peer_connection_simulcast_unittest.cc b/pc/peer_connection_simulcast_unittest.cc
index 3efc6cb..7618ce2 100644
--- a/pc/peer_connection_simulcast_unittest.cc
+++ b/pc/peer_connection_simulcast_unittest.cc
@@ -15,6 +15,8 @@
 #include "api/audio_codecs/builtin_audio_decoder_factory.h"
 #include "api/audio_codecs/builtin_audio_encoder_factory.h"
 #include "api/create_peerconnection_factory.h"
+#include "api/media_types.h"
+#include "api/rtc_error.h"
 #include "api/rtp_transceiver_interface.h"
 #include "api/uma_metrics.h"
 #include "api/video_codecs/builtin_video_decoder_factory.h"
@@ -254,6 +256,16 @@
   EXPECT_EQ(RTCErrorType::INVALID_PARAMETER, error.error().type());
 }
 
+// Validates that an error is returned when illegal RIDs are supplied.
+TEST_F(PeerConnectionSimulcastTests, ChecksForIllegalRidValues) {
+  auto pc_wrapper = CreatePeerConnectionWrapper();
+  auto pc = pc_wrapper->pc();
+  auto layers = CreateLayers({"f", "h", "~q"}, true);
+  auto init = CreateTransceiverInit(layers);
+  auto error = pc->AddTransceiver(cricket::MEDIA_TYPE_VIDEO, init);
+  EXPECT_EQ(RTCErrorType::INVALID_PARAMETER, error.error().type());
+}
+
 // Validates that a single RID is removed from the encoding layer.
 TEST_F(PeerConnectionSimulcastTests, SingleRidIsRemovedFromSessionDescription) {
   auto pc = CreatePeerConnectionWrapper();
diff --git a/pc/sdp_serializer.cc b/pc/sdp_serializer.cc
index 482dd07..7ebaffd 100644
--- a/pc/sdp_serializer.cc
+++ b/pc/sdp_serializer.cc
@@ -16,6 +16,7 @@
 
 #include "absl/algorithm/container.h"
 #include "api/jsep.h"
+#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/string_encode.h"
 #include "rtc_base/string_to_number.h"
@@ -328,6 +329,10 @@
     return ParseError("Invalid RID Description format. Too many arguments.");
   }
 
+  if (!IsLegalRsidName(tokens[0])) {
+    return ParseError("Invalid RID value: " + tokens[0] + ".");
+  }
+
   if (tokens[1] != kSendDirection && tokens[1] != kReceiveDirection) {
     return ParseError("Invalid RID direction. Supported values: send / recv.");
   }
diff --git a/pc/sdp_serializer_unittest.cc b/pc/sdp_serializer_unittest.cc
index e655f22..726d01d 100644
--- a/pc/sdp_serializer_unittest.cc
+++ b/pc/sdp_serializer_unittest.cc
@@ -469,6 +469,10 @@
     "1 send pt=",
     "1 send pt=abc",
     "1 recv ;;",
+    "~1 recv",
+    "1$2 send",
+    "1=2 send",
+    "1* send",
 };
 
 INSTANTIATE_TEST_SUITE_P(RidDescriptionDeserializationErrors,