diff --git a/Directory.Packages.props b/Directory.Packages.props
index cc1f867..9bcb6fb 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -18,7 +18,7 @@
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageVersion Include="NHibernate" Version="5.5.0" />
+    <PackageVersion Include="NHibernate" Version="[5.4,6.0)" />
     <PackageVersion Include="Nullable" Version="1.3.1" />
     <PackageVersion Include="NUnit" Version="4.0.1" />
     <PackageVersion Include="NUnit.Analyzers" Version="3.10.0" />
diff --git a/src/NHibernate.ObservableCollections.DemoApp/NHibernate.ObservableCollections.DemoApp.csproj b/src/NHibernate.ObservableCollections.DemoApp/NHibernate.ObservableCollections.DemoApp.csproj
index 7e523ae..c4a3dfe 100644
--- a/src/NHibernate.ObservableCollections.DemoApp/NHibernate.ObservableCollections.DemoApp.csproj
+++ b/src/NHibernate.ObservableCollections.DemoApp/NHibernate.ObservableCollections.DemoApp.csproj
@@ -26,6 +26,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.Data.SqlClient" />
+    <PackageReference Include="Iesi.Collections" />
     <PackageReference Include="NHibernate" />
     <PackageReference Include="Remotion.Linq" />
     <PackageReference Include="Remotion.Linq.EagerFetching" />
diff --git a/src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/OneToManyAssociationSync.cs b/src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/OneToManyAssociationSync.cs
index cf87ab3..bbafdef 100644
--- a/src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/OneToManyAssociationSync.cs
+++ b/src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/OneToManyAssociationSync.cs
@@ -70,7 +70,7 @@ public static void UpdateOneSide<T>(T thisManySide, object oldOneSide, object ne
         /// <summary>
         ///     Responds to add/remove events raised by the one-side's collection.
         /// </summary>
-        public void UpdateManySide(object sender, NotifyCollectionChangedEventArgs e)
+        public void UpdateManySide(object? sender, NotifyCollectionChangedEventArgs e)
         {
             if (e.Action == NotifyCollectionChangedAction.Add)
             {
diff --git a/src/NHibernate.ObservableCollections.Tests/NHibernate.ObservableCollections.Tests.csproj b/src/NHibernate.ObservableCollections.Tests/NHibernate.ObservableCollections.Tests.csproj
index 0984407..78232c6 100644
--- a/src/NHibernate.ObservableCollections.Tests/NHibernate.ObservableCollections.Tests.csproj
+++ b/src/NHibernate.ObservableCollections.Tests/NHibernate.ObservableCollections.Tests.csproj
@@ -25,9 +25,11 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="Iesi.Collections" />
     <PackageReference Include="LiquidTestReports.Markdown" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
     <PackageReference Include="Newtonsoft.Json" />
+    <PackageReference Include="NHibernate" />
     <PackageReference Include="NUnit" />
     <PackageReference Include="NUnit.Analyzers">
       <PrivateAssets>all</PrivateAssets>
diff --git a/src/NHibernate.ObservableCollections.Tests/ObservableCollectionTests.cs b/src/NHibernate.ObservableCollections.Tests/ObservableCollectionTests.cs
index ad0aee5..fa6e59f 100644
--- a/src/NHibernate.ObservableCollections.Tests/ObservableCollectionTests.cs
+++ b/src/NHibernate.ObservableCollections.Tests/ObservableCollectionTests.cs
@@ -3,7 +3,7 @@ namespace Iesi.Collections.Generic.Tests
     [TestFixture]
     public class ObservableCollectionTests
     {
-        private readonly List<int> _items = new();
+        private readonly List<int> _items = [];
 
         [OneTimeSetUp]
         public void SetupFixture()
diff --git a/src/NHibernate.ObservableCollections.Tests/ObservableSetTests.cs b/src/NHibernate.ObservableCollections.Tests/ObservableSetTests.cs
index 768c5f4..98e202e 100644
--- a/src/NHibernate.ObservableCollections.Tests/ObservableSetTests.cs
+++ b/src/NHibernate.ObservableCollections.Tests/ObservableSetTests.cs
@@ -3,7 +3,7 @@ namespace Iesi.Collections.Generic.Tests
     [TestFixture]
     public class ObservableSetTests
     {
-        private readonly List<int> _items = new();
+        private readonly List<int> _items = [];
 
         [OneTimeSetUp]
         public void SetupFixture()
diff --git a/src/NHibernate.ObservableCollections/ObservableCollection.cs b/src/NHibernate.ObservableCollections/ObservableCollection.cs
index 1b61e9e..0516dde 100644
--- a/src/NHibernate.ObservableCollections/ObservableCollection.cs
+++ b/src/NHibernate.ObservableCollections/ObservableCollection.cs
@@ -326,7 +326,7 @@ protected virtual void RemoveItemsRange(IEnumerable<T> collection)
                 }
                 else
                 {
-                    clusters[lastIndex = index] = lastCluster = new List<T> { item };
+                    clusters[lastIndex = index] = lastCluster = [item];
                 }
             }
 
diff --git a/src/NHibernate.ObservableCollections/ObservableSet.cs b/src/NHibernate.ObservableCollections/ObservableSet.cs
index 40971aa..5298668 100644
--- a/src/NHibernate.ObservableCollections/ObservableSet.cs
+++ b/src/NHibernate.ObservableCollections/ObservableSet.cs
@@ -518,7 +518,7 @@ private void OnCountPropertyChanged()
 
         internal static class EventArgsCache
         {
-            public static readonly List<T> NoItems = new();
+            public static readonly List<T> NoItems = [];
 
             public static readonly PropertyChangingEventArgs CountPropertyChanging = new(nameof(ObservableSet<T>.Count));
             public static readonly PropertyChangedEventArgs CountPropertyChanged = new(nameof(ObservableSet<T>.Count));
diff --git a/src/NHibernate.ObservableCollections/ReadOnlyObservableCollection.cs b/src/NHibernate.ObservableCollections/ReadOnlyObservableCollection.cs
index a5b6f01..eb97ab5 100644
--- a/src/NHibernate.ObservableCollections/ReadOnlyObservableCollection.cs
+++ b/src/NHibernate.ObservableCollections/ReadOnlyObservableCollection.cs
@@ -29,13 +29,15 @@ public ReadOnlyObservableCollection(ObservableCollection<T> collection) :
             ((INotifyPropertyChanged) Items).PropertyChanged += new PropertyChangedEventHandler(OnPropertyChanged);
         }
 
+#if !NET8_0_OR_GREATER
         /// <summary>
         ///     Gets an empty <see cref="ReadOnlyObservableCollection{T}" />.
         /// </summary>
         /// <value>An empty <see cref="ReadOnlyObservableCollection{T}" />.</value>
         /// <remarks>The returned instance is immutable and will always be empty.</remarks>
         public static ReadOnlyObservableCollection<T> Empty { get; } =
-            new ReadOnlyObservableCollection<T>(new ObservableCollection<T>());
+            new ReadOnlyObservableCollection<T>([]);
+#endif
 
         /// <summary>
         ///     CollectionChanged event (per <see cref="INotifyCollectionChanged" />).