diff --git a/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs b/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
index eb9d98750f758..285c4f26dee95 100644
--- a/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/IO/FileStream.cs
@@ -197,7 +197,9 @@ public FileStream(string path, FileMode mode, FileAccess access, FileShare share
         [Obsolete("This property has been deprecated.  Please use FileStream's SafeFileHandle property instead.  https://go.microsoft.com/fwlink/?linkid=14202")]
         public virtual IntPtr Handle => _strategy.Handle;
 
+        [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("macos")]
+        [UnsupportedOSPlatform("tvos")]
         public virtual void Lock(long position, long length)
         {
             if (position < 0 || length < 0)
@@ -212,7 +214,9 @@ public virtual void Lock(long position, long length)
             _strategy.Lock(position, length);
         }
 
+        [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("macos")]
+        [UnsupportedOSPlatform("tvos")]
         public virtual void Unlock(long position, long length)
         {
             if (position < 0 || length < 0)
diff --git a/src/libraries/System.Runtime/ref/System.Runtime.cs b/src/libraries/System.Runtime/ref/System.Runtime.cs
index d7d0aa9218bd9..19d1816ad465d 100644
--- a/src/libraries/System.Runtime/ref/System.Runtime.cs
+++ b/src/libraries/System.Runtime/ref/System.Runtime.cs
@@ -7329,7 +7329,9 @@ public override void EndWrite(System.IAsyncResult asyncResult) { }
         public override void Flush() { }
         public virtual void Flush(bool flushToDisk) { }
         public override System.Threading.Tasks.Task FlushAsync(System.Threading.CancellationToken cancellationToken) { throw null; }
+        [System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
         [System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
+        [System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
         public virtual void Lock(long position, long length) { }
         public override int Read(byte[] buffer, int offset, int count) { throw null; }
         public override int Read(System.Span<byte> buffer) { throw null; }
@@ -7338,7 +7340,9 @@ public virtual void Lock(long position, long length) { }
         public override int ReadByte() { throw null; }
         public override long Seek(long offset, System.IO.SeekOrigin origin) { throw null; }
         public override void SetLength(long value) { }
+        [System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
         [System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
+        [System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
         public virtual void Unlock(long position, long length) { }
         public override void Write(byte[] buffer, int offset, int count) { }
         public override void Write(System.ReadOnlySpan<byte> buffer) { }