diff --git a/src/dllmain.cpp b/src/dllmain.cpp
index bb683f8..ad09671 100644
--- a/src/dllmain.cpp
+++ b/src/dllmain.cpp
@@ -3,7 +3,6 @@
 
 #include "pch.h"
 
-#include "jpegls_bitmap_decoder.h"
 #include "jpegls_bitmap_encoder.h"
 #include "trace.h"
 #include "version.h"
@@ -17,6 +16,7 @@
 import guids;
 import util;
 import errors;
+import jpegls_bitmap_decoder;
 
 using std::array;
 using std::wstring;
diff --git a/src/jpegls-wic-codec.vcxproj b/src/jpegls-wic-codec.vcxproj
index ee693ea..8fb800a 100644
--- a/src/jpegls-wic-codec.vcxproj
+++ b/src/jpegls-wic-codec.vcxproj
@@ -69,7 +69,6 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
-    <ClInclude Include="jpegls_bitmap_decoder.h" />
     <ClInclude Include="jpegls_bitmap_encoder.h" />
     <ClInclude Include="jpegls_bitmap_frame_encode.h" />
     <ClInclude Include="macros.h" />
@@ -104,6 +103,14 @@
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">NotUsing</PrecompiledHeader>
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
     </ClCompile>
+    <ClCompile Include="jpegls_bitmap_decoder.ixx">
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
+    </ClCompile>
     <ClCompile Include="jpegls_bitmap_encoder.cpp" />
     <ClCompile Include="jpegls_bitmap_frame_decode.cpp">
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">NotUsing</PrecompiledHeader>
@@ -125,7 +132,14 @@
     <ClCompile Include="pch.cpp">
       <PrecompiledHeader>Create</PrecompiledHeader>
     </ClCompile>
-    <ClCompile Include="jpegls_bitmap_decoder.cpp" />
+    <ClCompile Include="jpegls_bitmap_decoder.cpp">
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
+    </ClCompile>
     <ClCompile Include="util.ixx">
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">NotUsing</PrecompiledHeader>
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">NotUsing</PrecompiledHeader>
diff --git a/src/jpegls-wic-codec.vcxproj.filters b/src/jpegls-wic-codec.vcxproj.filters
index 142fd86..6508210 100644
--- a/src/jpegls-wic-codec.vcxproj.filters
+++ b/src/jpegls-wic-codec.vcxproj.filters
@@ -21,9 +21,6 @@
     <ClInclude Include="trace.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="jpegls_bitmap_decoder.h">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="jpegls_bitmap_encoder.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -74,6 +71,7 @@
     <ClCompile Include="jpegls_bitmap_frame_decode.ixx">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="jpegls_bitmap_decoder.ixx" />
   </ItemGroup>
   <ItemGroup>
     <None Include="jpegls-wic-codec.def">
diff --git a/src/jpegls_bitmap_decoder.cpp b/src/jpegls_bitmap_decoder.cpp
index cfd92af..566dd9b 100644
--- a/src/jpegls_bitmap_decoder.cpp
+++ b/src/jpegls_bitmap_decoder.cpp
@@ -1,9 +1,7 @@
 // Copyright (c) Team CharLS.
 // SPDX-License-Identifier: BSD-3-Clause
 
-#include "pch.h"
-
-#include "jpegls_bitmap_decoder.h"
+module;
 
 #include "trace.h"
 #include "macros.h"
@@ -16,6 +14,8 @@
 #include <array>
 #include <mutex>
 
+module jpegls_bitmap_decoder;
+
 import class_factory;
 import guids;
 import util;
diff --git a/src/jpegls_bitmap_decoder.h b/src/jpegls_bitmap_decoder.h
deleted file mode 100644
index 736bc74..0000000
--- a/src/jpegls_bitmap_decoder.h
+++ /dev/null
@@ -1,6 +0,0 @@
-// Copyright (c) Team CharLS.
-// SPDX-License-Identifier: BSD-3-Clause
-
-#pragma once
-
-HRESULT create_jpegls_bitmap_decoder_factory(_In_ GUID const& interface_id, _Outptr_ void** result);
diff --git a/src/jpegls_bitmap_decoder.ixx b/src/jpegls_bitmap_decoder.ixx
index d22bb23..2d900c7 100644
--- a/src/jpegls_bitmap_decoder.ixx
+++ b/src/jpegls_bitmap_decoder.ixx
@@ -7,4 +7,4 @@ module;
 
 export module jpegls_bitmap_decoder;
 
-export HRESULT create_jpegls_bitmap_decoder_factory(_In_ GUID const& interface_id, _Outptr_ void** result);
+export HRESULT create_jpegls_bitmap_decoder_factory(GUID const& interface_id, void** result);