diff --git a/netwerk/protocol/http/HttpBaseChannel.h b/netwerk/protocol/http/HttpBaseChannel.h
index 92c48688729..bc4dfd5d390 100644
--- a/netwerk/protocol/http/HttpBaseChannel.h
+++ b/netwerk/protocol/http/HttpBaseChannel.h
@@ -467,6 +467,7 @@ class HttpBaseChannel : public nsHashPropertyBag,
   nsHttpResponseHead* GetResponseHead() const { return mResponseHead.get(); }
   nsHttpRequestHead* GetRequestHead() { return &mRequestHead; }
   nsHttpHeaderArray* GetResponseTrailers() const {
+    MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
     return mResponseTrailers.get();
   }
 
diff --git a/netwerk/protocol/http/HttpChannelChild.cpp b/netwerk/protocol/http/HttpChannelChild.cpp
index 265e04aae60..dc653676c7d 100644
--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -358,7 +358,7 @@ void HttpChannelChild::ProcessOnStartRequest(
   mAltDataInputStream = DeserializeIPCStream(aAltData.altDataInputStream());
 
   mEventQ->RunOrEnqueue(new NeckoTargetChannelFunctionEvent(
-      this, [self = UnsafePtr<HttpChannelChild>(this), aResponseHead,
+      this, [self = RefPtr<HttpChannelChild>(this), aResponseHead,
              aUseResponseHead, aRequestHeaders, aArgs]() {
         self->OnStartRequest(aResponseHead, aUseResponseHead, aRequestHeaders,
                              aArgs);
@@ -889,15 +889,15 @@ void HttpChannelChild::ProcessOnStopRequest(
 
   if (StaticPrefs::network_send_OnDataFinished()) {
     mEventQ->RunOrEnqueue(new ChannelFunctionEvent(
-        [self = UnsafePtr<HttpChannelChild>(this)]() {
+        [self = RefPtr<HttpChannelChild>(this)]() {
           return self->GetODATarget();
         },
-        [self = UnsafePtr<HttpChannelChild>(this), status = aChannelStatus]() {
+        [self = RefPtr<HttpChannelChild>(this), status = aChannelStatus]() {
           self->SendOnDataFinished(status);
         }));
   }
   mEventQ->RunOrEnqueue(new NeckoTargetChannelFunctionEvent(
-      this, [self = UnsafePtr<HttpChannelChild>(this), aChannelStatus, aTiming,
+      this, [self = RefPtr<HttpChannelChild>(this), aChannelStatus, aTiming,
              aResponseTrailers,
              consoleReports = CopyableTArray{aConsoleReports.Clone()},
              aFromSocketProcess]() mutable {
diff --git a/netwerk/protocol/http/HttpChannelParent.cpp b/netwerk/protocol/http/HttpChannelParent.cpp
index 621e7066f4f..5e583310518 100644
--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -1276,6 +1276,7 @@ HttpChannelParent::OnStartRequest(nsIRequest* aRequest) {
   mozilla::ipc::LoadInfoToParentLoadInfoForwarder(loadInfo,
                                                   &args.loadInfoForwarder());
 
+  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
   nsHttpResponseHead* responseHead = chan->GetResponseHead();
   bool useResponseHead = !!responseHead;
   nsHttpResponseHead cleanedUpResponseHead;
@@ -1357,6 +1358,10 @@ HttpChannelParent::OnStartRequest(nsIRequest* aRequest) {
   if (mIPCClosed) {
     rv = NS_ERROR_UNEXPECTED;
   } else {
+    MOZ_DIAGNOSTIC_ASSERT(
+        responseHead == &cleanedUpResponseHead ||
+            responseHead == chan->GetResponseHead(),
+        "mResponseHead changed between GetResponseHead and copy");
     nsHttpResponseHead newResponseHead = *responseHead;
     if (!mBgParent->OnStartRequest(
             std::move(newResponseHead), useResponseHead,
@@ -1918,6 +1923,7 @@ HttpChannelParent::StartRedirect(nsIChannel* newChannel, uint32_t redirectFlags,
   mozilla::ipc::LoadInfoToParentLoadInfoForwarder(loadInfo,
                                                   &loadInfoForwarderArg);
 
+  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
   nsHttpResponseHead* responseHead = mChannel->GetResponseHead();
 
   nsHttpResponseHead cleanedUpResponseHead;