diff --git a/src/installer/managed/Microsoft.NET.HostModel/ResourceUpdater.cs b/src/installer/managed/Microsoft.NET.HostModel/ResourceUpdater.cs
index e4791a6bb14e99..1873e38956038e 100644
--- a/src/installer/managed/Microsoft.NET.HostModel/ResourceUpdater.cs
+++ b/src/installer/managed/Microsoft.NET.HostModel/ResourceUpdater.cs
@@ -13,7 +13,7 @@ namespace Microsoft.NET.HostModel
     /// <summary>
     /// Provides methods for modifying the embedded native resources in a PE image.
     /// </summary>
-    public class ResourceUpdater : IDisposable
+    public sealed class ResourceUpdater : IDisposable
     {
         private readonly FileStream stream;
         private readonly PEReader _reader;
@@ -331,12 +331,15 @@ public void Dispose()
             GC.SuppressFinalize(this);
         }
 
-        public void Dispose(bool disposing)
+        private void Dispose(bool disposing)
         {
-            if (disposing && !leaveOpen)
+            if (disposing)
             {
                 _reader.Dispose();
-                stream.Dispose();
+                if (!leaveOpen)
+                {
+                    stream.Dispose();
+                }
             }
         }
     }
diff --git a/src/installer/tests/Microsoft.NET.HostModel.Tests/ResourceUpdaterTests.cs b/src/installer/tests/Microsoft.NET.HostModel.Tests/ResourceUpdaterTests.cs
index 30e3efdf1027db..2f25839507bbfa 100644
--- a/src/installer/tests/Microsoft.NET.HostModel.Tests/ResourceUpdaterTests.cs
+++ b/src/installer/tests/Microsoft.NET.HostModel.Tests/ResourceUpdaterTests.cs
@@ -23,7 +23,7 @@ class TempFile : IDisposable
         public TempFile()
         {
             _path = Path.GetTempFileName();
-            Stream = new FileStream(_path, FileMode.Open);
+            Stream = new FileStream(_path, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
         }
 
         public void Dispose()
@@ -169,6 +169,25 @@ void AddResource_AddTwoSameUShortTypeWithDifferName()
         }
     }
 
+    [Fact]
+    void DisposeWithLeaveOpenDisposesPEReader()
+    {
+        using var tempFile = GetCurrentAssemblyMemoryStream();
+        PEReader? peReader = null;
+
+        using (var updater = new ResourceUpdater(tempFile.Stream, leaveOpen: true))
+        {
+            FieldInfo? readerField = typeof(ResourceUpdater).GetField("_reader", BindingFlags.Instance | BindingFlags.NonPublic);
+            Assert.NotNull(readerField);
+            peReader = Assert.IsType<PEReader>(readerField.GetValue(updater));
+            _ = peReader.PEHeaders;
+        }
+
+        Assert.NotNull(peReader);
+
+        Assert.Throws<ObjectDisposedException>(() => _ = peReader!.PEHeaders);
+    }
+
     [Fact]
     void AddResourcesFromPEImage()
     {