--- a/netwerk/ipc/NeckoChannelParams.ipdlh
+++ b/netwerk/ipc/NeckoChannelParams.ipdlh
@@ -100,17 +100,17 @@ struct HttpChannelOpenArgs
   uint32_t                    referrerPolicy;
   OptionalURIParams           apiRedirectTo;
   OptionalURIParams           topWindowURI;
   uint32_t                    loadFlags;
   RequestHeaderTuples         requestHeaders;
   nsCString                   requestMethod;
   OptionalIPCStream           uploadStream;
   bool                        uploadStreamHasHeaders;
-  uint16_t                    priority;
+  int16_t                     priority;
   uint32_t                    classOfService;
   uint8_t                     redirectionLimit;
   bool                        allowPipelining;
   bool                        allowSTS;
   uint32_t                    thirdPartyFlags;
   bool                        resumeAt;
   uint64_t                    startPos;
   nsCString                   entityID;

--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -2955,16 +2955,16 @@ HttpChannelChild::ShouldInterceptURI(nsI
     rv = NS_GetSecureUpgradedURI(aURI, getter_AddRefs(upgradedURI));
     NS_ENSURE_SUCCESS(rv, false);
   }
 
   return ShouldIntercept(upgradedURI ? upgradedURI.get() : aURI);
 }
 
 mozilla::ipc::IPCResult
-HttpChannelChild::RecvSetPriority(const uint16_t& aPriority)
+HttpChannelChild::RecvSetPriority(const int16_t& aPriority)
 {
   mPriority = aPriority;
   return IPC_OK();
 }
 
 } // namespace net
 } // namespace mozilla

--- a/netwerk/protocol/http/HttpChannelChild.h
+++ b/netwerk/protocol/http/HttpChannelChild.h
@@ -148,17 +148,17 @@ protected:
   mozilla::ipc::IPCResult RecvFinishInterceptedRedirect() override;
 
   mozilla::ipc::IPCResult RecvReportSecurityMessage(const nsString& messageTag,
                                                     const nsString& messageCategory) override;
 
   mozilla::ipc::IPCResult RecvIssueDeprecationWarning(const uint32_t& warning,
                                                       const bool& asError) override;
 
-  mozilla::ipc::IPCResult RecvSetPriority(const uint16_t& aPriority) override;
+  mozilla::ipc::IPCResult RecvSetPriority(const int16_t& aPriority) override;
 
   bool GetAssociatedContentSecurity(nsIAssociatedContentSecurity** res = nullptr);
   virtual void DoNotifyListenerCleanup() override;
 
   NS_IMETHOD GetResponseSynthesized(bool* aSynthesized) override;
 
 private:
 

--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -295,17 +295,17 @@ HttpChannelParent::DoAsyncOpen(  const U
                                  const uint32_t&            aReferrerPolicy,
                                  const OptionalURIParams&   aAPIRedirectToURI,
                                  const OptionalURIParams&   aTopWindowURI,
                                  const uint32_t&            aLoadFlags,
                                  const RequestHeaderTuples& requestHeaders,
                                  const nsCString&           requestMethod,
                                  const OptionalIPCStream&   uploadStream,
                                  const bool&                uploadStreamHasHeaders,
-                                 const uint16_t&            priority,
+                                 const int16_t&             priority,
                                  const uint32_t&            classOfService,
                                  const uint8_t&             redirectionLimit,
                                  const bool&                allowPipelining,
                                  const bool&                allowSTS,
                                  const uint32_t&            thirdPartyFlags,
                                  const bool&                doResumeAt,
                                  const uint64_t&            startPos,
                                  const nsCString&           entityID,
@@ -616,19 +616,19 @@ HttpChannelParent::ConnectChannel(const 
       pbChannel->SetPrivate(mPBOverride == kPBOverride_Private ? true : false);
     }
   }
 
   return true;
 }
 
 mozilla::ipc::IPCResult
-HttpChannelParent::RecvSetPriority(const uint16_t& priority)
+HttpChannelParent::RecvSetPriority(const int16_t& priority)
 {
-  LOG(("HttpChannelParent::RecvSetPriority [this=%p, priority=%u]\n",
+  LOG(("HttpChannelParent::RecvSetPriority [this=%p, priority=%d]\n",
        this, priority));
 
   if (mChannel) {
     mChannel->SetPriority(priority);
   }
 
   nsCOMPtr<nsISupportsPriority> priorityRedirectChannel =
       do_QueryInterface(mRedirectChannel);

--- a/netwerk/protocol/http/HttpChannelParent.h
+++ b/netwerk/protocol/http/HttpChannelParent.h
@@ -114,17 +114,17 @@ protected:
                    const uint32_t&            referrerPolicy,
                    const OptionalURIParams&   internalRedirectUri,
                    const OptionalURIParams&   topWindowUri,
                    const uint32_t&            loadFlags,
                    const RequestHeaderTuples& requestHeaders,
                    const nsCString&           requestMethod,
                    const OptionalIPCStream&   uploadStream,
                    const bool&                uploadStreamHasHeaders,
-                   const uint16_t&            priority,
+                   const int16_t&             priority,
                    const uint32_t&            classOfService,
                    const uint8_t&             redirectionLimit,
                    const bool&                allowPipelining,
                    const bool&                allowSTS,
                    const uint32_t&            thirdPartyFlags,
                    const bool&                doResumeAt,
                    const uint64_t&            startPos,
                    const nsCString&           entityID,
@@ -143,17 +143,17 @@ protected:
                    const bool&                aBlockAuthPrompt,
                    const bool&                aSuspendAfterSynthesizeResponse,
                    const bool&                aAllowStaleCacheContent,
                    const nsCString&           aContentTypeHint,
                    const nsCString&           aChannelId,
                    const uint64_t&            aContentWindowId,
                    const nsCString&           aPreferredAlternativeType);
 
-  virtual mozilla::ipc::IPCResult RecvSetPriority(const uint16_t& priority) override;
+  virtual mozilla::ipc::IPCResult RecvSetPriority(const int16_t& priority) override;
   virtual mozilla::ipc::IPCResult RecvSetClassOfService(const uint32_t& cos) override;
   virtual mozilla::ipc::IPCResult RecvSetCacheTokenCachedCharset(const nsCString& charset) override;
   virtual mozilla::ipc::IPCResult RecvSuspend() override;
   virtual mozilla::ipc::IPCResult RecvResume() override;
   virtual mozilla::ipc::IPCResult RecvCancel(const nsresult& status) override;
   virtual mozilla::ipc::IPCResult RecvRedirect2Verify(const nsresult& result,
                                                       const RequestHeaderTuples& changedHeaders,
                                                       const uint32_t& loadFlags,

--- a/netwerk/protocol/http/PHttpChannel.ipdl
+++ b/netwerk/protocol/http/PHttpChannel.ipdl
@@ -170,14 +170,14 @@ child:
 
 both:
   // After receiving this message, the parent also calls
   // SendFinishInterceptedRedirect, and makes sure not to send any more messages
   // after that. When receiving this message, the child will call
   // Send__delete__() and complete the steps required to finish the redirect.
   async FinishInterceptedRedirect();
 
-  async SetPriority(uint16_t priority);
+  async SetPriority(int16_t priority);
 };
 
 
 } // namespace net
 } // namespace mozilla