diff --git a/p2p/base/dtls_transport.cc b/p2p/base/dtls_transport.cc
index 172d06188f..ce2793cb46 100644
--- a/p2p/base/dtls_transport.cc
+++ b/p2p/base/dtls_transport.cc
@@ -93,12 +93,17 @@ rtc::StreamResult StreamInterfaceChannel::Write(const void* data,
                                                 size_t* written,
                                                 int* error) {
   RTC_DCHECK_RUN_ON(&sequence_checker_);
-  // Always succeeds, since this is an unreliable transport anyway.
-  // TODO(zhihuang): Should this block if ice_transport_'s temporarily
-  // unwritable?
   rtc::PacketOptions packet_options;
-  ice_transport_->SendPacket(static_cast<const char*>(data), data_len,
-                             packet_options);
+  int sent = ice_transport_->SendPacket(static_cast<const char*>(data),
+                                        data_len, packet_options);
+  if (sent < 0) {
+    if (written) {
+      *written = 0;
+    }
+    return rtc::IsBlockingError(ice_transport_->GetError()) ? rtc::SR_BLOCK
+                                                            : rtc::SR_ERROR;
+  }
+
   if (written) {
     *written = data_len;
   }
diff --git a/p2p/base/dtls_transport_unittest.cc b/p2p/base/dtls_transport_unittest.cc
index 851c1ea131..4957b46a50 100644
--- a/p2p/base/dtls_transport_unittest.cc
+++ b/p2p/base/dtls_transport_unittest.cc
@@ -421,6 +421,16 @@ TEST_F(DtlsTransportTest, TestTransferDtls) {
   TestTransfer(1000, 100, /*srtp=*/false);
 }
 
+// Connect with DTLS, and fail to write, to ensure errors are propagated.
+TEST_F(DtlsTransportTest, TestWriteFailsOverDtls) {
+  PrepareDtls(rtc::KT_DEFAULT);
+  ASSERT_TRUE(Connect());
+  client1_.fake_ice_transport()->SetError(EAGAIN);
+  int res = client1_.dtls_transport()->SendPacket("hello", 5,
+                                                  rtc::PacketOptions(), 0);
+  EXPECT_EQ(res, -1);
+}
+
 // Connect with DTLS, combine multiple DTLS records into one packet.
 // Our DTLS implementation doesn't do this, but other implementations may;
 // see https://tools.ietf.org/html/rfc6347#section-4.1.1.
diff --git a/p2p/base/fake_ice_transport.h b/p2p/base/fake_ice_transport.h
index 8b52fe934c..7f934446e4 100644
--- a/p2p/base/fake_ice_transport.h
+++ b/p2p/base/fake_ice_transport.h
@@ -302,6 +302,10 @@ class FakeIceTransport : public IceTransportInternal {
       return -1;
     }
 
+    if (error_ != 0) {
+      return -1;
+    }
+
     send_packet_.AppendData(data, len);
     if (!combine_outgoing_packets_ || send_packet_.size() > len) {
       rtc::CopyOnWriteBuffer packet(std::move(send_packet_));
@@ -338,7 +342,17 @@ class FakeIceTransport : public IceTransportInternal {
     }
   }
 
-  int GetError() override { return 0; }
+  // Sets the error that is returned by `GetError`. If an error is set (i.e.
+  // non-zero), `SendPacket` will return -1.
+  void SetError(int error) {
+    RTC_DCHECK_RUN_ON(network_thread_);
+    error_ = error;
+  }
+
+  int GetError() override {
+    RTC_DCHECK_RUN_ON(network_thread_);
+    return error_;
+  }
 
   rtc::CopyOnWriteBuffer last_sent_packet() {
     RTC_DCHECK_RUN_ON(network_thread_);
@@ -421,6 +435,7 @@ class FakeIceTransport : public IceTransportInternal {
   rtc::CopyOnWriteBuffer last_sent_packet_ RTC_GUARDED_BY(network_thread_);
   rtc::Thread* const network_thread_;
   webrtc::ScopedTaskSafetyDetached task_safety_;
+  int error_ RTC_GUARDED_BY(network_thread_) = 0;
 };
 
 class FakeIceTransportWrapper : public webrtc::IceTransportInterface {