diff --git a/MoreLinq.Test/AppendTest.cs b/MoreLinq.Test/AppendTest.cs
index 736ba6498..55ff31597 100644
--- a/MoreLinq.Test/AppendTest.cs
+++ b/MoreLinq.Test/AppendTest.cs
@@ -15,6 +15,8 @@
 // limitations under the License.
 #endregion
 
+#if !NET471_OR_GREATER && !NETSTANDARD1_6_OR_GREATER && !NETCOREAPP2_0_OR_GREATER
+
 namespace MoreLinq.Test
 {
     using System.Collections.Generic;
@@ -90,3 +92,5 @@ public void AppendWithSharedSource()
         }
     }
 }
+
+#endif
diff --git a/MoreLinq.Test/DistinctByTest.cs b/MoreLinq.Test/DistinctByTest.cs
index 7035578f2..377c9a318 100644
--- a/MoreLinq.Test/DistinctByTest.cs
+++ b/MoreLinq.Test/DistinctByTest.cs
@@ -15,6 +15,8 @@
 // limitations under the License.
 #endregion
 
+#if !NET6_0_OR_GREATER
+
 namespace MoreLinq.Test
 {
     using System;
@@ -61,3 +63,5 @@ public void DistinctByIsLazyWithComparer()
         }
     }
 }
+
+#endif
diff --git a/MoreLinq.Test/Enumerable.cs b/MoreLinq.Test/Enumerable.cs
index f7795af4e..ae22e31cd 100644
--- a/MoreLinq.Test/Enumerable.cs
+++ b/MoreLinq.Test/Enumerable.cs
@@ -45,6 +45,11 @@ public static bool Any<TSource>(this IEnumerable<TSource> source) =>
         public static bool Any<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) =>
             LinqEnumerable.Any(source, predicate);
 
+#if NET471_OR_GREATER || NET6_0_OR_GREATER
+        public static IEnumerable<TSource> Append<TSource> (this IEnumerable<TSource> source, TSource element) =>
+            LinqEnumerable.Append(source, element);
+#endif
+
         public static IEnumerable<TSource> AsEnumerable<TSource>(this IEnumerable<TSource> source) =>
             LinqEnumerable.AsEnumerable(source);
 
diff --git a/MoreLinq.Test/PrependTest.cs b/MoreLinq.Test/PrependTest.cs
index eaaad5c81..3a4f938d1 100644
--- a/MoreLinq.Test/PrependTest.cs
+++ b/MoreLinq.Test/PrependTest.cs
@@ -15,6 +15,8 @@
 // limitations under the License.
 #endregion
 
+#if !NET471_OR_GREATER && !NETSTANDARD1_6_OR_GREATER && !NETCOREAPP2_0_OR_GREATER
+
 namespace MoreLinq.Test
 {
     using System.Collections.Generic;
@@ -89,3 +91,5 @@ public void PrependWithSharedSource()
         }
     }
 }
+
+#endif
diff --git a/MoreLinq.Test/SkipLastTest.cs b/MoreLinq.Test/SkipLastTest.cs
index df7b19680..f6bbf7796 100644
--- a/MoreLinq.Test/SkipLastTest.cs
+++ b/MoreLinq.Test/SkipLastTest.cs
@@ -15,6 +15,8 @@
 // limitations under the License.
 #endregion
 
+#if !NETSTANDARD2_1 && !NETCOREAPP2_0_OR_GREATER
+
 namespace MoreLinq.Test
 {
     using System.Collections.Generic;
@@ -68,3 +70,5 @@ public void SkipLastUsesCollectionCountAtIterationTime()
         }
     }
 }
+
+#endif
diff --git a/MoreLinq.Test/TakeLastTest.cs b/MoreLinq.Test/TakeLastTest.cs
index 5779f4cfc..fc0347bf6 100644
--- a/MoreLinq.Test/TakeLastTest.cs
+++ b/MoreLinq.Test/TakeLastTest.cs
@@ -15,6 +15,8 @@
 // limitations under the License.
 #endregion
 
+#if !NETSTANDARD2_1 && !NETCOREAPP2_0_OR_GREATER
+
 namespace MoreLinq.Test
 {
     using NUnit.Framework;
@@ -89,3 +91,5 @@ static void AssertTakeLast<T>(ICollection<T> input, int count, Action<IEnumerabl
         }
     }
 }
+
+#endif
diff --git a/MoreLinq/Append.cs b/MoreLinq/Append.cs
index b081bbd83..3a02d376b 100644
--- a/MoreLinq/Append.cs
+++ b/MoreLinq/Append.cs
@@ -31,7 +31,11 @@ static partial class MoreEnumerable
         /// <returns>A sequence consisting of the head elements and the given tail element.</returns>
         /// <remarks>This operator uses deferred execution and streams its results.</remarks>
 
+#if NET471_OR_GREATER || NETSTANDARD1_6_OR_GREATER || NETCOREAPP2_0_OR_GREATER
+        public static IEnumerable<T> Append<T>(IEnumerable<T> head, T tail)
+#else
         public static IEnumerable<T> Append<T>(this IEnumerable<T> head, T tail)
+#endif
         {
             if (head == null) throw new ArgumentNullException(nameof(head));
             return head is PendNode<T> node
diff --git a/MoreLinq/CompatibilitySuppressions.xml b/MoreLinq/CompatibilitySuppressions.xml
index da1602414..227399b89 100644
--- a/MoreLinq/CompatibilitySuppressions.xml
+++ b/MoreLinq/CompatibilitySuppressions.xml
@@ -1,6 +1,69 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- https://learn.microsoft.com/en-us/dotnet/fundamentals/package-validation/diagnostic-ids -->
 <Suppressions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.AppendExtension</Target>
+    <Left>lib/net462/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.PrependExtension</Target>
+    <Left>lib/net462/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.AppendExtension</Target>
+    <Left>lib/net6.0/MoreLinq.dll</Left>
+    <Right>lib/net6.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.PrependExtension</Target>
+    <Left>lib/net6.0/MoreLinq.dll</Left>
+    <Right>lib/net6.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.AppendExtension</Target>
+    <Left>lib/netstandard2.0/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.PrependExtension</Target>
+    <Left>lib/netstandard2.0/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.AppendExtension</Target>
+    <Left>lib/netstandard2.1/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.1/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:MoreLinq.Extensions.PrependExtension</Target>
+    <Left>lib/netstandard2.1/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.1/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Append``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/net462/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:MoreLinq.MoreEnumerable.Concat``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
@@ -8,6 +71,20 @@
     <Right>lib/netstandard2.0/MoreLinq.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Prepend``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/net462/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Append``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/net6.0/MoreLinq.dll</Left>
+    <Right>lib/net6.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:MoreLinq.MoreEnumerable.Concat``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
@@ -15,6 +92,20 @@
     <Right>lib/net6.0/MoreLinq.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Prepend``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/net6.0/MoreLinq.dll</Left>
+    <Right>lib/net6.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Append``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/netstandard2.0/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:MoreLinq.MoreEnumerable.Concat``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
@@ -22,6 +113,20 @@
     <Right>lib/netstandard2.0/MoreLinq.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Prepend``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/netstandard2.0/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.0/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Append``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/netstandard2.1/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.1/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:MoreLinq.MoreEnumerable.Concat``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
@@ -29,6 +134,13 @@
     <Right>lib/netstandard2.1/MoreLinq.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:MoreLinq.MoreEnumerable.Prepend``1(System.Collections.Generic.IEnumerable{``0},``0)</Target>
+    <Left>lib/netstandard2.1/MoreLinq.dll</Left>
+    <Right>lib/netstandard2.1/MoreLinq.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>PKV006</DiagnosticId>
     <Target>.NETStandard,Version=v1.0</Target>
diff --git a/MoreLinq/DistinctBy.cs b/MoreLinq/DistinctBy.cs
index a05faab82..1079ff814 100644
--- a/MoreLinq/DistinctBy.cs
+++ b/MoreLinq/DistinctBy.cs
@@ -38,10 +38,15 @@ static partial class MoreEnumerable
         /// <returns>A sequence consisting of distinct elements from the source sequence,
         /// comparing them by the specified key projection.</returns>
 
+#if NET6_0_OR_GREATER
+        public static IEnumerable<TSource> DistinctBy<TSource, TKey>(IEnumerable<TSource> source,
+            Func<TSource, TKey> keySelector)
+#else
         public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source,
             Func<TSource, TKey> keySelector)
+#endif
         {
-            return source.DistinctBy(keySelector, null);
+            return DistinctBy(source, keySelector, null);
         }
 
         /// <summary>
@@ -62,8 +67,13 @@ public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TS
         /// <returns>A sequence consisting of distinct elements from the source sequence,
         /// comparing them by the specified key projection.</returns>
 
+#if NET6_0_OR_GREATER
+        public static IEnumerable<TSource> DistinctBy<TSource, TKey>(IEnumerable<TSource> source,
+            Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer)
+#else
         public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source,
             Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer)
+#endif
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
             if (keySelector == null) throw new ArgumentNullException(nameof(keySelector));
diff --git a/MoreLinq/Prepend.cs b/MoreLinq/Prepend.cs
index 06f5a0f27..fb82e8538 100644
--- a/MoreLinq/Prepend.cs
+++ b/MoreLinq/Prepend.cs
@@ -41,7 +41,11 @@ static partial class MoreEnumerable
         /// The <c>result</c> variable, when iterated over, will yield
         /// 0, 1, 2 and 3, in turn.
 
+#if NET471_OR_GREATER || NETSTANDARD1_6_OR_GREATER || NETCOREAPP2_0_OR_GREATER
+        public static IEnumerable<TSource> Prepend<TSource>(IEnumerable<TSource> source, TSource value)
+#else
         public static IEnumerable<TSource> Prepend<TSource>(this IEnumerable<TSource> source, TSource value)
+#endif
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
             return source is PendNode<TSource> node
diff --git a/MoreLinq/PublicAPI/net6.0/PublicAPI.Unshipped.txt b/MoreLinq/PublicAPI/net6.0/PublicAPI.Unshipped.txt
index b4ddb014c..8959c7eec 100644
--- a/MoreLinq/PublicAPI/net6.0/PublicAPI.Unshipped.txt
+++ b/MoreLinq/PublicAPI/net6.0/PublicAPI.Unshipped.txt
@@ -1,2 +1,18 @@
 #nullable enable
+*REMOVED*static MoreLinq.MoreEnumerable.Append<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
 *REMOVED*static MoreLinq.MoreEnumerable.Concat<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+*REMOVED*static MoreLinq.MoreEnumerable.Prepend<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.DistinctBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, TKey>! keySelector) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.DistinctBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, TKey>! keySelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.SkipLast<T>(this System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
+*REMOVED*static MoreLinq.MoreEnumerable.TakeLast<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, int count) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source) -> System.Collections.Generic.HashSet<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Collections.Generic.IEqualityComparer<TSource>? comparer) -> System.Collections.Generic.HashSet<TSource>!
+static MoreLinq.MoreEnumerable.Append<T>(System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+static MoreLinq.MoreEnumerable.DistinctBy<TSource, TKey>(System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, TKey>! keySelector) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.DistinctBy<TSource, TKey>(System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, TKey>! keySelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.Prepend<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.SkipLast<T>(System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
+static MoreLinq.MoreEnumerable.TakeLast<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, int count) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.ToHashSet<TSource>(System.Collections.Generic.IEnumerable<TSource>! source) -> System.Collections.Generic.HashSet<TSource>!
+static MoreLinq.MoreEnumerable.ToHashSet<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, System.Collections.Generic.IEqualityComparer<TSource>? comparer) -> System.Collections.Generic.HashSet<TSource>!
diff --git a/MoreLinq/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt b/MoreLinq/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
index b4ddb014c..056e1801b 100644
--- a/MoreLinq/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
+++ b/MoreLinq/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
@@ -1,2 +1,6 @@
 #nullable enable
+*REMOVED*static MoreLinq.MoreEnumerable.Append<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
 *REMOVED*static MoreLinq.MoreEnumerable.Concat<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+*REMOVED*static MoreLinq.MoreEnumerable.Prepend<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.Append<T>(System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+static MoreLinq.MoreEnumerable.Prepend<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
diff --git a/MoreLinq/PublicAPI/netstandard2.1/PublicAPI.Unshipped.txt b/MoreLinq/PublicAPI/netstandard2.1/PublicAPI.Unshipped.txt
index b4ddb014c..b025e7aed 100644
--- a/MoreLinq/PublicAPI/netstandard2.1/PublicAPI.Unshipped.txt
+++ b/MoreLinq/PublicAPI/netstandard2.1/PublicAPI.Unshipped.txt
@@ -1,2 +1,14 @@
 #nullable enable
+*REMOVED*static MoreLinq.MoreEnumerable.Append<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
 *REMOVED*static MoreLinq.MoreEnumerable.Concat<T>(this System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+*REMOVED*static MoreLinq.MoreEnumerable.Prepend<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.SkipLast<T>(this System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
+*REMOVED*static MoreLinq.MoreEnumerable.TakeLast<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, int count) -> System.Collections.Generic.IEnumerable<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source) -> System.Collections.Generic.HashSet<TSource>!
+*REMOVED*static MoreLinq.MoreEnumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Collections.Generic.IEqualityComparer<TSource>? comparer) -> System.Collections.Generic.HashSet<TSource>!
+static MoreLinq.MoreEnumerable.Append<T>(System.Collections.Generic.IEnumerable<T>! head, T tail) -> System.Collections.Generic.IEnumerable<T>!
+static MoreLinq.MoreEnumerable.Prepend<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, TSource value) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.SkipLast<T>(System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
+static MoreLinq.MoreEnumerable.TakeLast<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, int count) -> System.Collections.Generic.IEnumerable<TSource>!
+static MoreLinq.MoreEnumerable.ToHashSet<TSource>(System.Collections.Generic.IEnumerable<TSource>! source) -> System.Collections.Generic.HashSet<TSource>!
+static MoreLinq.MoreEnumerable.ToHashSet<TSource>(System.Collections.Generic.IEnumerable<TSource>! source, System.Collections.Generic.IEqualityComparer<TSource>? comparer) -> System.Collections.Generic.HashSet<TSource>!
diff --git a/MoreLinq/SkipLast.cs b/MoreLinq/SkipLast.cs
index 0483f3e74..c88cec5e4 100644
--- a/MoreLinq/SkipLast.cs
+++ b/MoreLinq/SkipLast.cs
@@ -33,7 +33,11 @@ static partial class MoreEnumerable
         /// An <see cref="IEnumerable{T}"/> containing the source sequence elements except for the bypassed ones at the end.
         /// </returns>
 
+#if NETSTANDARD2_1 || NETCOREAPP2_0_OR_GREATER
+        public static IEnumerable<T> SkipLast<T>(IEnumerable<T> source, int count)
+#else
         public static IEnumerable<T> SkipLast<T>(this IEnumerable<T> source, int count)
+#endif
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
 
diff --git a/MoreLinq/TakeLast.cs b/MoreLinq/TakeLast.cs
index 6619ff196..88eac7a8e 100644
--- a/MoreLinq/TakeLast.cs
+++ b/MoreLinq/TakeLast.cs
@@ -46,7 +46,11 @@ static partial class MoreEnumerable
         /// 56 and 78 in turn.
         /// </example>
 
+#if NETSTANDARD2_1 || NETCOREAPP2_0_OR_GREATER
+        public static IEnumerable<TSource> TakeLast<TSource>(IEnumerable<TSource> source, int count)
+#else
         public static IEnumerable<TSource> TakeLast<TSource>(this IEnumerable<TSource> source, int count)
+#endif
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
 
diff --git a/MoreLinq/ToHashSet.cs b/MoreLinq/ToHashSet.cs
index 7301ed357..1f6dc8bd1 100644
--- a/MoreLinq/ToHashSet.cs
+++ b/MoreLinq/ToHashSet.cs
@@ -35,9 +35,13 @@ static partial class MoreEnumerable
         /// This evaluates the input sequence completely.
         /// </remarks>
 
+#if NETSTANDARD2_1 || NET472_OR_GREATER || NETCOREAPP2_0_OR_GREATER
+        public static HashSet<TSource> ToHashSet<TSource>(IEnumerable<TSource> source)
+#else
         public static HashSet<TSource> ToHashSet<TSource>(this IEnumerable<TSource> source)
+#endif
         {
-            return source.ToHashSet(null);
+            return ToHashSet(source, null);
         }
 
         /// <summary>
@@ -53,7 +57,11 @@ public static HashSet<TSource> ToHashSet<TSource>(this IEnumerable<TSource> sour
         /// This evaluates the input sequence completely.
         /// </remarks>
 
+#if NETSTANDARD2_1 || NET472_OR_GREATER || NETCOREAPP2_0_OR_GREATER
+        public static HashSet<TSource> ToHashSet<TSource>(IEnumerable<TSource> source, IEqualityComparer<TSource>? comparer)
+#else
         public static HashSet<TSource> ToHashSet<TSource>(this IEnumerable<TSource> source, IEqualityComparer<TSource>? comparer)
+#endif
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
             return new HashSet<TSource>(source, comparer);
diff --git a/bld/ExtensionsGenerator/Program.cs b/bld/ExtensionsGenerator/Program.cs
index f9cc083c2..87dba483d 100644
--- a/bld/ExtensionsGenerator/Program.cs
+++ b/bld/ExtensionsGenerator/Program.cs
@@ -235,7 +235,16 @@ from md in g
                 select
                     MethodDeclaration(md.ReturnType, md.Identifier)
                         .WithAttributeLists(md.AttributeLists)
-                        .WithModifiers(md.Modifiers)
+                        .WithModifiers(
+                            TokenList(md.Modifiers[0] // assume at least one modifier, like public
+                                        .WithLeadingTrivia(
+                                            from lt in md.Modifiers[0].LeadingTrivia
+                                            where lt.Kind() is not (SyntaxKind.DisabledTextTrivia
+                                                                    or SyntaxKind.IfDirectiveTrivia
+                                                                    or SyntaxKind.ElseDirectiveTrivia
+                                                                    or SyntaxKind.EndIfDirectiveTrivia)
+                                            select lt))
+                                .AddRange(md.Modifiers.Skip(1)))
                         .WithTypeParameterList(md.TypeParameterList)
                         .WithConstraintClauses(md.ConstraintClauses)
                         .WithParameterList(md.ParameterList)