diff --git a/pc/peer_connection_signaling_unittest.cc b/pc/peer_connection_signaling_unittest.cc
index 8df90b7bfa..250efc8dc5 100644
--- a/pc/peer_connection_signaling_unittest.cc
+++ b/pc/peer_connection_signaling_unittest.cc
@@ -1051,7 +1051,7 @@ TEST_P(PeerConnectionSignalingTest, MidAttributeMaxLength) {
       "1C:2C:74:01:8D:50:67:23\r\n"
       "a=setup:actpass\r\n"
       // Too long mid attribute.
-      "a=mid:01234567890123456\r\n"
+      "a=mid:0123456789012345678901234567890123\r\n"
       "a=sendrecv\r\n"
       "a=msid:stream track\r\n"
       "a=rtcp-mux\r\n"
diff --git a/pc/sdp_offer_answer.cc b/pc/sdp_offer_answer.cc
index 8f5cec2f03..4332cd6df8 100644
--- a/pc/sdp_offer_answer.cc
+++ b/pc/sdp_offer_answer.cc
@@ -124,7 +124,8 @@ const char kSimulcastDisabled[] = "WebRTC.PeerConnection.Simulcast.Disabled";
 static const int kRtcpCnameLength = 16;
 
 // The maximum length of the MID attribute.
-static constexpr size_t kMidMaxSize = 16;
+// TODO(bugs.webrtc.org/12517) - reduce to 16 again.
+static constexpr size_t kMidMaxSize = 32;
 
 const char kDefaultStreamId[] = "default";
 // NOTE: Duplicated in peer_connection.cc:
@@ -446,21 +447,25 @@ bool VerifyIceUfragPwdPresent(
 
 RTCError ValidateMids(const cricket::SessionDescription& description) {
   std::set<std::string> mids;
+  size_t max_length = 0;
   for (const cricket::ContentInfo& content : description.contents()) {
     if (content.name.empty()) {
       LOG_AND_RETURN_ERROR(RTCErrorType::INVALID_PARAMETER,
                            "A media section is missing a MID attribute.");
     }
+    max_length = std::max(max_length, content.name.size());
     if (content.name.size() > kMidMaxSize) {
       LOG_AND_RETURN_ERROR(RTCErrorType::INVALID_PARAMETER,
                            "The MID attribute exceeds the maximum supported "
-                           "length of 16 characters.");
+                           "length of 32 characters.");
     }
     if (!mids.insert(content.name).second) {
       LOG_AND_RETURN_ERROR(RTCErrorType::INVALID_PARAMETER,
                            "Duplicate a=mid value '" + content.name + "'.");
     }
   }
+  RTC_HISTOGRAM_COUNTS_LINEAR("WebRTC.PeerConnection.Mid.Size", max_length, 0,
+                              31, 32);
   return RTCError::OK();
 }