diff --git a/talk/app/webrtc/webrtcsdp.cc b/talk/app/webrtc/webrtcsdp.cc
index 72a72bf43e..a93977d6d9 100644
--- a/talk/app/webrtc/webrtcsdp.cc
+++ b/talk/app/webrtc/webrtcsdp.cc
@@ -1770,6 +1770,8 @@ void BuildCandidate(const std::vector<Candidate>& candidates,
       type = kCandidateRelay;
     } else {
       ASSERT(false);
+      // Never write out candidates if we don't know the type.
+      continue;
     }
 
     InitAttrLine(kAttributeCandidate, &os);
diff --git a/webrtc/p2p/base/transport.cc b/webrtc/p2p/base/transport.cc
index dfc7d34b43..df452fdf31 100644
--- a/webrtc/p2p/base/transport.cc
+++ b/webrtc/p2p/base/transport.cc
@@ -559,6 +559,12 @@ void Transport::OnChannelRequestSignaling_s() {
 
 void Transport::OnChannelCandidateReady(TransportChannelImpl* channel,
                                         const Candidate& candidate) {
+  // We should never signal peer-reflexive candidates.
+  if (candidate.type() == PRFLX_PORT_TYPE) {
+    ASSERT(false);
+    return;
+  }
+
   ASSERT(worker_thread()->IsCurrent());
   rtc::CritScope cs(&crit_);
   ready_candidates_.push_back(candidate);