diff --git a/pc/data_channel_controller.cc b/pc/data_channel_controller.cc
index 92cdba3..36e8be1 100644
--- a/pc/data_channel_controller.cc
+++ b/pc/data_channel_controller.cc
@@ -22,17 +22,10 @@
 namespace webrtc {
 
 DataChannelController::~DataChannelController() {
-#if RTC_DCHECK_IS_ON
-  // `sctp_data_channels_n_` might be empty while `sctp_data_channels_` is
-  // not. An example of that is when the `DataChannelController` goes out of
-  // scope with outstanding channels that have been properly terminated on the
-  // network thread but not yet cleared from `sctp_data_channels_`. However,
-  // if `sctp_data_channels_n_` is not empty, then `sctp_data_channels_n_` and
-  // sctp_data_channels_ should hold the same contents.
-  if (!sctp_data_channels_n_.empty()) {
-    RTC_DCHECK_EQ(sctp_data_channels_n_.size(), sctp_data_channels_.size());
-  }
-#endif
+  RTC_DCHECK(sctp_data_channels_n_.empty())
+      << "Missing call to TeardownDataChannelTransport_n?";
+  RTC_DCHECK(!signaling_safety_.flag()->alive())
+      << "Missing call to PrepareForShutdown?";
 }
 
 bool DataChannelController::HasDataChannelsForTest() const {
@@ -167,7 +160,7 @@
 
 void DataChannelController::PrepareForShutdown() {
   RTC_DCHECK_RUN_ON(signaling_thread());
-  signaling_safety_.reset();
+  signaling_safety_.reset(PendingTaskSafetyFlag::CreateDetachedInactive());
 }
 
 void DataChannelController::TeardownDataChannelTransport_n() {
diff --git a/pc/data_channel_controller.h b/pc/data_channel_controller.h
index f71e7a4..fa6c13e 100644
--- a/pc/data_channel_controller.h
+++ b/pc/data_channel_controller.h
@@ -102,6 +102,10 @@
 
   void OnSctpDataChannelClosed(SctpDataChannel* channel);
 
+ protected:
+  rtc::Thread* network_thread() const;
+  rtc::Thread* signaling_thread() const;
+
  private:
   // Parses and handles open messages.  Returns true if the message is an open
   // message and should be considered to be handled, false otherwise.
@@ -138,9 +142,6 @@
   std::vector<rtc::scoped_refptr<SctpDataChannel>>::iterator FindChannel(
       StreamId stream_id);
 
-  rtc::Thread* network_thread() const;
-  rtc::Thread* signaling_thread() const;
-
   // Plugin transport used for data channels.  Pointer may be accessed and
   // checked from any thread, but the object may only be touched on the
   // network thread.
diff --git a/pc/data_channel_controller_unittest.cc b/pc/data_channel_controller_unittest.cc
index 470c01c..9b66fac 100644
--- a/pc/data_channel_controller_unittest.cc
+++ b/pc/data_channel_controller_unittest.cc
@@ -43,6 +43,23 @@
   MOCK_METHOD(bool, IsReadyToSend, (), (const, override));
 };
 
+// Convenience class for tests to ensure that shutdown methods for DCC
+// are consistently called. In practice SdpOfferAnswerHandler will call
+// TeardownDataChannelTransport_n on the network thread when destroying the
+// data channel transport and PeerConnection calls PrepareForShutdown() from
+// within PeerConnection::Close(). The DataChannelControllerForTest class mimics
+// behavior by calling those methods from within its destructor.
+class DataChannelControllerForTest : public DataChannelController {
+ public:
+  explicit DataChannelControllerForTest(PeerConnectionInternal* pc)
+      : DataChannelController(pc) {}
+
+  ~DataChannelControllerForTest() override {
+    network_thread()->BlockingCall([&] { TeardownDataChannelTransport_n(); });
+    PrepareForShutdown();
+  }
+};
+
 class DataChannelControllerTest : public ::testing::Test {
  protected:
   DataChannelControllerTest()
@@ -65,11 +82,11 @@
 };
 
 TEST_F(DataChannelControllerTest, CreateAndDestroy) {
-  DataChannelController dcc(pc_.get());
+  DataChannelControllerForTest dcc(pc_.get());
 }
 
 TEST_F(DataChannelControllerTest, CreateDataChannelEarlyRelease) {
-  DataChannelController dcc(pc_.get());
+  DataChannelControllerForTest dcc(pc_.get());
   auto ret = dcc.InternalCreateDataChannelWithProxy(
       "label", InternalDataChannelInit(DataChannelInit()));
   ASSERT_TRUE(ret.ok());
@@ -79,7 +96,7 @@
 }
 
 TEST_F(DataChannelControllerTest, CreateDataChannelEarlyClose) {
-  DataChannelController dcc(pc_.get());
+  DataChannelControllerForTest dcc(pc_.get());
   EXPECT_FALSE(dcc.HasDataChannelsForTest());
   EXPECT_FALSE(dcc.HasUsedDataChannels());
   auto ret = dcc.InternalCreateDataChannelWithProxy(
@@ -89,12 +106,13 @@
   EXPECT_TRUE(dcc.HasDataChannelsForTest());
   EXPECT_TRUE(dcc.HasUsedDataChannels());
   channel->Close();
+  run_loop_.Flush();
   EXPECT_FALSE(dcc.HasDataChannelsForTest());
   EXPECT_TRUE(dcc.HasUsedDataChannels());
 }
 
 TEST_F(DataChannelControllerTest, CreateDataChannelLateRelease) {
-  auto dcc = std::make_unique<DataChannelController>(pc_.get());
+  auto dcc = std::make_unique<DataChannelControllerForTest>(pc_.get());
   auto ret = dcc->InternalCreateDataChannelWithProxy(
       "label", InternalDataChannelInit(DataChannelInit()));
   ASSERT_TRUE(ret.ok());
@@ -104,7 +122,7 @@
 }
 
 TEST_F(DataChannelControllerTest, CloseAfterControllerDestroyed) {
-  auto dcc = std::make_unique<DataChannelController>(pc_.get());
+  auto dcc = std::make_unique<DataChannelControllerForTest>(pc_.get());
   auto ret = dcc->InternalCreateDataChannelWithProxy(
       "label", InternalDataChannelInit(DataChannelInit()));
   ASSERT_TRUE(ret.ok());
@@ -114,7 +132,7 @@
 }
 
 TEST_F(DataChannelControllerTest, AsyncChannelCloseTeardown) {
-  DataChannelController dcc(pc_.get());
+  DataChannelControllerForTest dcc(pc_.get());
   auto ret = dcc.InternalCreateDataChannelWithProxy(
       "label", InternalDataChannelInit(DataChannelInit()));
   ASSERT_TRUE(ret.ok());
@@ -162,7 +180,7 @@
                                                          : rtc::SSL_CLIENT);
   });
 
-  DataChannelController dcc(pc_.get());
+  DataChannelControllerForTest dcc(pc_.get());
   pc_->network_thread()->BlockingCall(
       [&] { dcc.set_data_channel_transport(&transport); });
 
@@ -189,8 +207,8 @@
     return rtc::SSL_CLIENT;
   });
 
-  DataChannelController dcc(pc_.get());
-  NiceMock<MockDataChannelTransport> transport;
+  NiceMock<MockDataChannelTransport> transport;  // Wider scope than `dcc`.
+  DataChannelControllerForTest dcc(pc_.get());
   pc_->network_thread()->BlockingCall(
       [&] { dcc.set_data_channel_transport(&transport); });
 
diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index f365601..fdbd32b 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -588,6 +588,8 @@
     // The event log must outlive call (and any other object that uses it).
     event_log_.reset();
   });
+
+  data_channel_controller_.PrepareForShutdown();
 }
 
 RTCError PeerConnection::Initialize(