diff --git a/pc/webrtc_sdp.cc b/pc/webrtc_sdp.cc
index aa98e480ef..7a2aeae3a4 100644
--- a/pc/webrtc_sdp.cc
+++ b/pc/webrtc_sdp.cc
@@ -2992,17 +2992,17 @@ bool ParseContent(const std::string& message,
     if (IsLineType(line, kLineTypeSessionBandwidth)) {
       std::string bandwidth;
       std::string bandwidth_type;
-      if (HasAttribute(line, kApplicationSpecificBandwidth)) {
-        if (!GetValue(line, kApplicationSpecificBandwidth, &bandwidth, error)) {
-          return false;
-        }
-        bandwidth_type = kApplicationSpecificBandwidth;
-      } else if (HasAttribute(line, kTransportSpecificBandwidth)) {
-        if (!GetValue(line, kTransportSpecificBandwidth, &bandwidth, error)) {
-          return false;
-        }
-        bandwidth_type = kTransportSpecificBandwidth;
-      } else {
+      if (!rtc::tokenize_first(line.substr(kLinePrefixLength),
+                               kSdpDelimiterColonChar, &bandwidth_type,
+                               &bandwidth)) {
+        return ParseFailed(
+            line,
+            "b= syntax error, does not match b=<modifier>:<bandwidth-value>.",
+            error);
+      }
+      if (!(bandwidth_type == kApplicationSpecificBandwidth ||
+            bandwidth_type == kTransportSpecificBandwidth)) {
+        // Ignore unknown bandwidth types.
         continue;
       }
       int b = 0;
diff --git a/pc/webrtc_sdp_unittest.cc b/pc/webrtc_sdp_unittest.cc
index 2a4c36d61f..9f81129663 100644
--- a/pc/webrtc_sdp_unittest.cc
+++ b/pc/webrtc_sdp_unittest.cc
@@ -2645,6 +2645,24 @@ TEST_F(WebRtcSdpTest, DeserializeSessionDescriptionWithTiasBandwidth) {
   EXPECT_TRUE(CompareSessionDescription(jdesc_, jdesc_with_bandwidth));
 }
 
+TEST_F(WebRtcSdpTest,
+       DeserializeSessionDescriptionWithUnknownBandwidthModifier) {
+  JsepSessionDescription jdesc_with_bandwidth(kDummyType);
+  std::string sdp_with_bandwidth = kSdpFullString;
+  InjectAfter("a=mid:video_content_name\r\na=sendrecv\r\n",
+              "b=unknown:100000\r\n", &sdp_with_bandwidth);
+  InjectAfter("a=mid:audio_content_name\r\na=sendrecv\r\n",
+              "b=unknown:50000\r\n", &sdp_with_bandwidth);
+  EXPECT_TRUE(SdpDeserialize(sdp_with_bandwidth, &jdesc_with_bandwidth));
+  VideoContentDescription* vcd = GetFirstVideoContentDescription(&desc_);
+  vcd->set_bandwidth(-1);
+  AudioContentDescription* acd = GetFirstAudioContentDescription(&desc_);
+  acd->set_bandwidth(-1);
+  ASSERT_TRUE(jdesc_.Initialize(desc_.Clone(), jdesc_.session_id(),
+                                jdesc_.session_version()));
+  EXPECT_TRUE(CompareSessionDescription(jdesc_, jdesc_with_bandwidth));
+}
+
 TEST_F(WebRtcSdpTest, DeserializeSessionDescriptionWithIceOptions) {
   JsepSessionDescription jdesc_with_ice_options(kDummyType);
   std::string sdp_with_ice_options = kSdpFullString;
@@ -3369,6 +3387,13 @@ TEST_F(WebRtcSdpTest, DeserializeSdpWithInvalidAttributeValue) {
   // bandwidth
   ExpectParseFailureWithNewLines("a=mid:video_content_name\r\n",
                                  "b=AS:badvalue\r\n", "b=AS:badvalue");
+  ExpectParseFailureWithNewLines("a=mid:video_content_name\r\n", "b=AS\r\n",
+                                 "b=AS");
+  ExpectParseFailureWithNewLines("a=mid:video_content_name\r\n", "b=AS:\r\n",
+                                 "b=AS:");
+  ExpectParseFailureWithNewLines("a=mid:video_content_name\r\n",
+                                 "b=AS:12:34\r\n", "b=AS:12:34");
+
   // rtcp-fb
   ExpectParseFailureWithNewLines("a=mid:video_content_name\r\n",
                                  "a=rtcp-fb:badvalue nack\r\n",