diff --git a/src/macos/stella.xcodeproj/project.pbxproj b/src/macos/stella.xcodeproj/project.pbxproj
index e58dc9639..7947b42e0 100644
--- a/src/macos/stella.xcodeproj/project.pbxproj
+++ b/src/macos/stella.xcodeproj/project.pbxproj
@@ -1948,8 +1948,6 @@
 		2D6050CC0898776500C6DE89 /* emucore */ = {
 			isa = PBXGroup;
 			children = (
-				E050876C25A1337400E4B62A /* OSystemStandalone.cxx */,
-				E050876D25A1337400E4B62A /* OSystemStandalone.hxx */,
 				DC1B2EBE1E50036100F62837 /* AmigaMouse.hxx */,
 				DC1B2EC01E50036100F62837 /* AtariMouse.hxx */,
 				DC487FB40DA5350900E12499 /* AtariVox.cxx */,
@@ -2111,6 +2109,8 @@
 				DCC527CD10B9DA19005E1287 /* NullDev.hxx */,
 				2DDBEB7408457B7D00812C11 /* OSystem.cxx */,
 				2DDBEB7508457B7D00812C11 /* OSystem.hxx */,
+				E050876C25A1337400E4B62A /* OSystemStandalone.cxx */,
+				E050876D25A1337400E4B62A /* OSystemStandalone.hxx */,
 				2DE2DF820627AE34006BEC99 /* Paddles.cxx */,
 				2DE2DF830627AE34006BEC99 /* Paddles.hxx */,
 				DC479401258C56B800F52462 /* PlusROM.cxx */,
diff --git a/src/windows/Stella.vcxproj b/src/windows/Stella.vcxproj
index d649bb9e2..5b8892d41 100644
--- a/src/windows/Stella.vcxproj
+++ b/src/windows/Stella.vcxproj
@@ -762,6 +762,7 @@
     <ClCompile Include="..\emucore\FBSurface.cxx" />
     <ClCompile Include="..\emucore\Lightgun.cxx" />
     <ClCompile Include="..\emucore\MindLink.cxx" />
+    <ClCompile Include="..\emucore\OSystemStandalone.cxx" />
     <ClCompile Include="..\emucore\PlusROM.cxx" />
     <ClCompile Include="..\emucore\PointingDevice.cxx" />
     <ClCompile Include="..\emucore\ProfilingRunner.cxx" />
@@ -1831,6 +1832,7 @@
     <ClInclude Include="..\emucore\FrameBufferConstants.hxx" />
     <ClInclude Include="..\emucore\Lightgun.hxx" />
     <ClInclude Include="..\emucore\MindLink.hxx" />
+    <ClInclude Include="..\emucore\OSystemStandalone.hxx" />
     <ClInclude Include="..\emucore\PlusROM.hxx" />
     <ClInclude Include="..\emucore\PointingDevice.hxx" />
     <ClInclude Include="..\emucore\ProfilingRunner.hxx" />
diff --git a/src/windows/Stella.vcxproj.filters b/src/windows/Stella.vcxproj.filters
index 5adf56e36..6fbfdcbff 100644
--- a/src/windows/Stella.vcxproj.filters
+++ b/src/windows/Stella.vcxproj.filters
@@ -1104,6 +1104,9 @@
     <ClCompile Include="..\common\repository\sqlite\StellaDb.cxx">
       <Filter>Source Files\repository\sqlite</Filter>
     </ClCompile>
+    <ClCompile Include="..\emucore\OSystemStandalone.cxx">
+      <Filter>Source Files\emucore</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\common\bspf.hxx">
@@ -2273,6 +2276,9 @@
     <ClInclude Include="..\common\repository\sqlite\StellaDb.hxx">
       <Filter>Header Files\repository\sqlite</Filter>
     </ClInclude>
+    <ClInclude Include="..\emucore\OSystemStandalone.hxx">
+      <Filter>Header Files\emucore</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="stella.ico">