diff --git a/Build/libHttpClient.Android/build.gradle b/Build/libHttpClient.Android/build.gradle
index 110bfff8..94e31a9a 100644
--- a/Build/libHttpClient.Android/build.gradle
+++ b/Build/libHttpClient.Android/build.gradle
@@ -1,7 +1,7 @@
 apply plugin: "com.android.library"
 
 android {
-    compileSdkVersion 31
+    compileSdkVersion 34
     ndkVersion "27.2.12479018"
 
     defaultConfig {
diff --git a/Build/libHttpClient.GDK.props b/Build/libHttpClient.GDK.props
index 118ac231..7ef22c71 100644
--- a/Build/libHttpClient.GDK.props
+++ b/Build/libHttpClient.GDK.props
@@ -106,7 +106,12 @@
       <TreatWarningAsError>true</TreatWarningAsError>
       <SupportJustMyCode>false</SupportJustMyCode>
       <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
-      <PreprocessorDefinitions>__WRL_NO_DEFAULT_LIB__;_LIB;$(libHttpClientDefine);%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <!--
+        ASIO_DISABLE_SERIAL_PORT: GDK builds compile with NOSERIALCOMM (no DCB),
+        which breaks asio's win_iocp_serial_port_service. asio is pulled in via
+        websocketpp; we don't use its serial-port transport, so disable it.
+      -->
+      <PreprocessorDefinitions>__WRL_NO_DEFAULT_LIB__;_LIB;ASIO_DISABLE_SERIAL_PORT;$(libHttpClientDefine);%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <AdditionalIncludeDirectories Condition="'$(Platform)'!='x64' AND '$(Platform)'!='ARM64'">%(AdditionalIncludeDirectories);$(GDKCrossPlatformPath)GRDK\ExtensionLibraries\Xbox.XCurl.API\Include</AdditionalIncludeDirectories>
       <ControlFlowGuard>Guard</ControlFlowGuard>
       <AdditionalOptions>/Zc:__cplusplus /ZH:SHA_256 /bigobj /Zi %(AdditionalOptions)</AdditionalOptions>
diff --git a/Build/libHttpClient.Linux/CMakeLists.txt b/Build/libHttpClient.Linux/CMakeLists.txt
index 58a52f1b..87622d76 100644
--- a/Build/libHttpClient.Linux/CMakeLists.txt
+++ b/Build/libHttpClient.Linux/CMakeLists.txt
@@ -226,6 +226,7 @@ if (HC_ENABLE_WEBSOCKET_COMPRESSION AND NOT HC_NOWEBSOCKETS)
         PRIVATE
         "${PROJECT_NAME}"
         Threads::Threads
+        ${CMAKE_DL_LIBS} # Required for dlopen/dlsym referenced by linked libcrypto in some configurations
     )
 
     if (NOT BUILD_SHARED_LIBS)
diff --git a/Include/httpClient/httpClient.h b/Include/httpClient/httpClient.h
index 331ae17f..8744a764 100644
--- a/Include/httpClient/httpClient.h
+++ b/Include/httpClient/httpClient.h
@@ -1043,7 +1043,13 @@ enum class HCWebSocketOptions : uint32_t
     CompressionClientNoContextTakeover = 0x00000004
 };
 
+// DEFINE_ENUM_FLAG_OPERATORS expands to C++ inline operators returning
+// HCWebSocketOptions&, which is not legal inside the surrounding extern "C"
+// block. Re-enter C++ linkage just for the macro expansion so callers can
+// still combine flags with |, &, ^, etc.
+extern "C++" {
 DEFINE_ENUM_FLAG_OPERATORS(HCWebSocketOptions)
+} // extern "C++"
 
 /// <summary>
 /// Creates an WebSocket handle.
diff --git a/Samples/UWP-Http/Http.vcxproj b/Samples/UWP-Http/Http.vcxproj
index 322568d6..d423c1da 100644
--- a/Samples/UWP-Http/Http.vcxproj
+++ b/Samples/UWP-Http/Http.vcxproj
@@ -9,6 +9,7 @@
   <ItemDefinitionGroup>
     <ClCompile>
       <PreprocessorDefinitions>_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <TreatWarningAsError Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">false</TreatWarningAsError>
     </ClCompile>
   </ItemDefinitionGroup>
   <ItemGroup>