diff --git a/src/libraries/System.IO.FileSystem/src/System.IO.FileSystem.csproj b/src/libraries/System.IO.FileSystem/src/System.IO.FileSystem.csproj
index 0c36fbf8b216e..f7d2d0c5499a7 100644
--- a/src/libraries/System.IO.FileSystem/src/System.IO.FileSystem.csproj
+++ b/src/libraries/System.IO.FileSystem/src/System.IO.FileSystem.csproj
@@ -5,6 +5,9 @@
     <TargetFrameworks>$(NetCoreAppCurrent)-Windows_NT;$(NetCoreAppCurrent)-Unix;$(NetCoreAppCurrent)-Browser</TargetFrameworks>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetsBrowser)' == 'true'">
+    <DefineConstants>$(DefineConstants);TARGET_BROWSER</DefineConstants>
+  </PropertyGroup>
   <ItemGroup>
     <!-- System.IO.Enumeration.FileSystemEntry is not correctly parsed by CsharpAnalyser so we are skipping this type from autogenerated typeforwards file.  -->
     <GenFacadesIgnoreMissingType Include="System.IO.Enumeration.FileSystemEntry" />
@@ -177,8 +180,6 @@
              Link="Interop\Unix\Interop.Errors.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\Interop.IOErrors.cs"
              Link="Interop\Unix\Interop.IOErrors.cs" />
-    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetEUid.cs"
-             Link="Common\Interop\Unix\Interop.GetEUid.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.MountPoints.cs"
              Link="Common\Interop\Unix\Interop.MountPoints.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Permissions.cs"
@@ -203,8 +204,6 @@
              Link="Common\Interop\Unix\Interop.ChMod.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.CopyFile.cs"
              Link="Common\Interop\Unix\Interop.CopyFile.cs" />
-    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetEGid.cs"
-             Link="Common\Interop\Unix\Interop.GetEGid.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.LChflags.cs"
              Link="Common\Interop\Unix\Interop.LChflags.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Link.cs"
@@ -228,6 +227,12 @@
     <Compile Include="System\IO\FileSystem.Unix.cs" />
     <Compile Include="System\IO\FileSystemInfo.Unix.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetEUid.cs"
+             Link="Common\Interop\Unix\Interop.GetEUid.cs" />
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.GetEGid.cs"
+             Link="Common\Interop\Unix\Interop.GetEGid.cs" />
+  </ItemGroup>
   <!-- Unix references -->
   <ItemGroup Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true'">
     <Reference Include="System.Threading" />
diff --git a/src/libraries/System.IO.FileSystem/src/System/IO/FileStatus.Unix.cs b/src/libraries/System.IO.FileSystem/src/System/IO/FileStatus.Unix.cs
index 086c09039f02e..e32d3a1c54dfd 100644
--- a/src/libraries/System.IO.FileSystem/src/System/IO/FileStatus.Unix.cs
+++ b/src/libraries/System.IO.FileSystem/src/System/IO/FileStatus.Unix.cs
@@ -39,7 +39,12 @@ internal static void Initialize(
         internal bool IsReadOnly(ReadOnlySpan<char> path, bool continueOnError = false)
         {
             EnsureStatInitialized(path, continueOnError);
+#if TARGET_BROWSER
+            const Interop.Sys.Permissions readBit = Interop.Sys.Permissions.S_IRUSR;
+            const Interop.Sys.Permissions writeBit = Interop.Sys.Permissions.S_IWUSR;
+#else
             Interop.Sys.Permissions readBit, writeBit;
+
             if (_fileStatus.Uid == Interop.Sys.GetEUid())
             {
                 // User effectively owns the file
@@ -58,6 +63,7 @@ internal bool IsReadOnly(ReadOnlySpan<char> path, bool continueOnError = false)
                 readBit = Interop.Sys.Permissions.S_IROTH;
                 writeBit = Interop.Sys.Permissions.S_IWOTH;
             }
+#endif
 
             return ((_fileStatus.Mode & (int)readBit) != 0 && // has read permission
                 (_fileStatus.Mode & (int)writeBit) == 0);     // but not write permission