diff --git a/CHANGES.md b/CHANGES.md
index b55f854f429..1f9a22923ac 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -44,6 +44,7 @@ To be released.
      -  Removed `IBlockChainStates.GetValidatorSet(BlockHash?)` method.
  -  (@planetarium/tx)  Remove the `T` generic argument of `SignedTx<T>`.
     [[#3512]]
+ -  (Libplanet.Common) Removed `EnumerableExtensions` class.  [[#3625], [#3626]]
 
 ### Backward-incompatible network protocol changes
 
@@ -82,6 +83,8 @@ To be released.
 [#3540]: https://github.com/planetarium/libplanet/pull/3540
 [#3583]: https://github.com/planetarium/libplanet/pull/3583
 [#3589]: https://github.com/planetarium/libplanet/pull/3589
+[#3625]: https://github.com/planetarium/libplanet/issues/3625
+[#3626]: https://github.com/planetarium/libplanet/pull/3626
 
 
 Version 3.9.5
diff --git a/Libplanet.Common/EnumerableExtensions.cs b/Libplanet.Common/EnumerableExtensions.cs
deleted file mode 100644
index fc473932620..00000000000
--- a/Libplanet.Common/EnumerableExtensions.cs
+++ /dev/null
@@ -1,102 +0,0 @@
-#nullable disable
-using System;
-using System.Collections.Generic;
-#if !NETSTANDARD2_1
-using System.Diagnostics;
-#endif
-using System.Linq;
-
-namespace Libplanet.Common
-{
-    public static class EnumerableExtensions
-    {
-        /// <summary>
-        /// Similar to <see
-        /// cref="Enumerable.Max{TSource,TResult}(IEnumerable{TSource}, Func{TSource, TResult})"/>
-        /// method, but it returns the source element with the maximum value of the given
-        /// <paramref name="selector"/>, instead of the maximum value.
-        /// </summary>
-        /// <param name="source">The source enumerable.</param>
-        /// <param name="selector">A function to select the value to compare.</param>
-        /// <typeparam name="TSource">The type of the source elements.</typeparam>
-        /// <typeparam name="TComparable">The type of the value to compare.</typeparam>
-        /// <returns>The source element with the maximum value of the given
-        /// <paramref name="selector"/>.</returns>
-        /// <exception cref="InvalidOperationException">Thrown when the source sequence is empty.
-        /// </exception>
-        public static TSource Greatest<TSource, TComparable>(
-            this IEnumerable<TSource> source,
-            Func<TSource, TComparable> selector
-        )
-            where TComparable : IComparable<TComparable>
-        {
-            bool first = true;
-            TSource greatestElement = default;
-            TComparable greatestValue = default;
-            foreach (TSource element in source)
-            {
-                TComparable value = selector(element);
-                if (first || value.CompareTo(greatestValue) > 0)
-                {
-                    greatestValue = value;
-                    greatestElement = element;
-                }
-
-                first = false;
-            }
-
-            if (first)
-            {
-                throw new InvalidOperationException("Sequence contains no elements.");
-            }
-
-            return greatestElement;
-        }
-
-#if !NETSTANDARD2_1
-        // Copied from .NET Runtime <https://git.io/JL8X6#L115-L154>
-        public static IEnumerable<TSource> SkipLast<TSource>(
-            this IEnumerable<TSource> source,
-            int count
-        )
-        {
-            if (source == null)
-            {
-                throw new ArgumentNullException(nameof(source));
-            }
-
-            return count <= 0 ? source.Skip(0) : SkipLastIterator(source, count);
-        }
-
-        private static IEnumerable<TSource> SkipLastIterator<TSource>(
-            IEnumerable<TSource> source,
-            int count
-        )
-        {
-            Debug.Assert(source != null, $"The {nameof(source)} must not be null.");
-            Debug.Assert(count > 0, $"The {count} must be greater than zero.");
-
-            var queue = new Queue<TSource>();
-
-            using IEnumerator<TSource> e = source.GetEnumerator();
-            while (e.MoveNext())
-            {
-                if (queue.Count == count)
-                {
-                    do
-                    {
-                        yield return queue.Dequeue();
-                        queue.Enqueue(e.Current);
-                    }
-                    while (e.MoveNext());
-                    break;
-                }
-                else
-                {
-                    queue.Enqueue(e.Current);
-                }
-            }
-        }
-#endif
-    }
-}
diff --git a/Libplanet.Net/Swarm.cs b/Libplanet.Net/Swarm.cs
index 9d4d8317cff..6e1d057343e 100644
--- a/Libplanet.Net/Swarm.cs
+++ b/Libplanet.Net/Swarm.cs
@@ -11,7 +11,9 @@
 using Bencodex;
 using Libplanet.Action;
 using Libplanet.Blockchain;
+#if NETSTANDARD2_0
 using Libplanet.Common;
+#endif
 using Libplanet.Crypto;
 using Libplanet.Net.Consensus;
 using Libplanet.Net.Messages;
@@ -594,7 +596,7 @@ public async Task PreloadAsync(
                 Block localTip = BlockChain.Tip;
                 IBlockExcerpt topmostTip = peersWithExcerpts
                     .Select(pair => pair.Item2)
-                    .Greatest(tip => tip.Index);
+                    .Aggregate((prev, next) => prev.Index > next.Index ? prev : next);
                 if (topmostTip.Index - (i > 0 ? tipDeltaThreshold : 0L) <= localTip.Index)
                 {
                     const string msg =