diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61bb729..eb88270 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - X10D: `DateTime.Age(DateTime)` and `DateTimeOffset.Age(DateTimeOffset)` parameter renamed from `asOf` to `referenceDate`.
 
+### Removed
+
+- X10D: Removed `IEnumerable<T>.ConcatOne` - this functionality already exists with `Append`. 
+
 ## [3.2.0] - 2023-04-03
 
 ### Added
diff --git a/X10D/src/Linq/EnumerableExtensions.cs b/X10D/src/Linq/EnumerableExtensions.cs
index 05004c9..39d4002 100644
--- a/X10D/src/Linq/EnumerableExtensions.cs
+++ b/X10D/src/Linq/EnumerableExtensions.cs
@@ -9,32 +9,6 @@ namespace X10D.Linq;
 /// </summary>
 public static class EnumerableExtensions
 {
-    /// <summary>
-    ///     Concatenates a single value to the end of a sequence.
-    /// </summary>
-    /// <param name="source">The source sequence.</param>
-    /// <param name="value">The value to concatenate to the end of the source sequence.</param>
-    /// <typeparam name="TSource">The type of the elements in <paramref name="source" />.</typeparam>
-    /// <returns>
-    ///     An <see cref="IEnumerable{T}" /> that contains the concatenated elements of the input sequence, and the specified
-    ///     value.
-    /// </returns>
-    /// <exception cref="ArgumentNullException"><paramref name="source" /> is <see langword="null" />.</exception>
-    public static IEnumerable<TSource> ConcatOne<TSource>(this IEnumerable<TSource> source, TSource value)
-    {
-        if (source is null)
-        {
-            throw new ArgumentNullException(nameof(source));
-        }
-
-        foreach (TSource item in source)
-        {
-            yield return item;
-        }
-
-        yield return value;
-    }
-
     /// <summary>
     ///     Filters a sequence of values by omitting elements that match a specified value.
     /// </summary>