diff --git a/Directory.Build.targets b/Directory.Build.targets
index 1dc7daa031..60014e02b9 100644
--- a/Directory.Build.targets
+++ b/Directory.Build.targets
@@ -80,7 +80,7 @@
     <DebugType>portable</DebugType>
   </PropertyGroup>
 
-  <!-- Features in .NET Standard 2.1, .NET 5.x, .NET 6.x, .NET 7.x, .NET 8.x, and .NET 9.x only -->
+  <!-- Features in .NET Standard 2.1, .NET Core 3.x, .NET 5.x, .NET 6.x, .NET 7.x, .NET 8.x, and .NET 9.x only -->
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.1' Or $(TargetFramework.StartsWith('netcoreapp3.')) Or $(TargetFramework.StartsWith('net5.')) Or $(TargetFramework.StartsWith('net6.')) Or $(TargetFramework.StartsWith('net7.')) Or $(TargetFramework.StartsWith('net8.')) Or $(TargetFramework.StartsWith('net9.')) ">
 
     <DefineConstants>$(DefineConstants);FEATURE_ARRAY_FILL</DefineConstants>
@@ -93,6 +93,13 @@
 
   </PropertyGroup>
 
+  <!-- Features in .NET Standard 2.1, .NET Core 2.1-2.2, .NET Core 3.x, .NET 5.x, .NET 6.x, .NET 7.x, .NET 8.x, and .NET 9.x only -->
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.1' Or '$(TargetFramework)' == 'netcoreapp2.1' Or '$(TargetFramework)' == 'netcoreapp2.2' Or $(TargetFramework.StartsWith('netcoreapp3.')) Or $(TargetFramework.StartsWith('net5.')) Or $(TargetFramework.StartsWith('net6.')) Or $(TargetFramework.StartsWith('net7.')) Or $(TargetFramework.StartsWith('net8.')) Or $(TargetFramework.StartsWith('net9.')) ">
+
+    <DefineConstants>$(DefineConstants);FEATURE_STRING_CONTAINS_STRINGCOMPARISON</DefineConstants>
+
+  </PropertyGroup>
+
   <!-- Features in .NET Standard 2.x, .NET Core 2.x, .NET Core 3.x, .NET 5.x, .NET 6.x, .NET 7.x, .NET 8.x, and .NET 9.x -->
   <PropertyGroup Condition=" $(TargetFramework.StartsWith('netstandard2.')) Or $(TargetFramework.StartsWith('netcoreapp2.')) Or $(TargetFramework.StartsWith('netcoreapp3.')) Or $(TargetFramework.StartsWith('net5.')) Or $(TargetFramework.StartsWith('net6.')) Or $(TargetFramework.StartsWith('net7.')) Or $(TargetFramework.StartsWith('net8.')) Or $(TargetFramework.StartsWith('net9.')) ">
 
diff --git a/src/Lucene.Net.Tests.AllProjects/Support/ExceptionHandling/TestExceptionExtensions.cs b/src/Lucene.Net.Tests.AllProjects/Support/ExceptionHandling/TestExceptionExtensions.cs
index 776f6ac06a..862db3661a 100644
--- a/src/Lucene.Net.Tests.AllProjects/Support/ExceptionHandling/TestExceptionExtensions.cs
+++ b/src/Lucene.Net.Tests.AllProjects/Support/ExceptionHandling/TestExceptionExtensions.cs
@@ -7,6 +7,10 @@
 using System.Linq;
 using Assert = Lucene.Net.TestFramework.Assert;
 
+#if !FEATURE_STRING_CONTAINS_STRINGCOMPARISON
+using Lucene.Net.Support.Text;
+#endif
+
 namespace Lucene.Net.Support.ExceptionHandling
 {
     /*
diff --git a/src/Lucene.Net.Tests/Support/Text/TestStringExtensions.cs b/src/Lucene.Net.Tests/Support/Text/TestStringExtensions.cs
new file mode 100644
index 0000000000..b041d86ad6
--- /dev/null
+++ b/src/Lucene.Net.Tests/Support/Text/TestStringExtensions.cs
@@ -0,0 +1,48 @@
+using Lucene.Net.Attributes;
+using Lucene.Net.Util;
+using NUnit.Framework;
+#if !FEATURE_STRING_CONTAINS_STRINGCOMPARISON
+using System;
+#endif
+
+namespace Lucene.Net.Support.Text
+{
+    /*
+     * Licensed to the Apache Software Foundation (ASF) under one or more
+     * contributor license agreements.  See the NOTICE file distributed with
+     * this work for additional information regarding copyright ownership.
+     * The ASF licenses this file to You under the Apache License, Version 2.0
+     * (the "License"); you may not use this file except in compliance with
+     * the License.  You may obtain a copy of the License at
+     *
+     *     http://www.apache.org/licenses/LICENSE-2.0
+     *
+     * Unless required by applicable law or agreed to in writing, software
+     * distributed under the License is distributed on an "AS IS" BASIS,
+     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     * See the License for the specific language governing permissions and
+     * limitations under the License.
+     */
+
+    [TestFixture, LuceneNetSpecific]
+    public class TestStringExtensions : LuceneTestCase
+    {
+        [Test]
+        public void TestContainsAny()
+        {
+            Assert.IsTrue("hello".ContainsAny(new[] { 'h', 'e', 'l', 'o' }));
+            Assert.IsFalse("hello".ContainsAny(new[] { 'x', 'y', 'z' }));
+        }
+
+#if !FEATURE_STRING_CONTAINS_STRINGCOMPARISON
+        [Test]
+        public void TestContainsWithStringComparison()
+        {
+            Assert.IsTrue("hello".Contains("ell", StringComparison.Ordinal));
+            Assert.IsFalse("hello".Contains("world", StringComparison.Ordinal));
+            Assert.IsTrue("hello".Contains("ELL", StringComparison.OrdinalIgnoreCase));
+            Assert.IsFalse("hello".Contains("WORLD", StringComparison.OrdinalIgnoreCase));
+        }
+#endif
+    }
+}
diff --git a/src/Lucene.Net/Support/Text/StringExtensions.cs b/src/Lucene.Net/Support/Text/StringExtensions.cs
index eae0842233..e15c607089 100644
--- a/src/Lucene.Net/Support/Text/StringExtensions.cs
+++ b/src/Lucene.Net/Support/Text/StringExtensions.cs
@@ -48,5 +48,26 @@ public static bool ContainsAny(this string input, char[] charsToCompare)
             }
             return false;
         }
+
+#if !FEATURE_STRING_CONTAINS_STRINGCOMPARISON
+        /// <summary>
+        /// Returns <c>true</c> if <paramref name="input"/> contains <paramref name="value"/>
+        /// using the specified <paramref name="comparison"/>.
+        /// </summary>
+        /// <param name="input">The string in which to seek <paramref name="value"/>.</param>
+        /// <param name="value">The string to check for.</param>
+        /// <param name="comparison">The <see cref="StringComparison"/> to use.</param>
+        /// <returns><c>true</c> if <paramref name="value"/> is found, otherwise; <c>false</c>.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool Contains(this string input, string value, StringComparison comparison)
+        {
+            if (input is null)
+                throw new ArgumentNullException(nameof(input));
+            if (value is null)
+                throw new ArgumentNullException(nameof(value));
+
+            return input.IndexOf(value, comparison) >= 0;
+        }
+#endif
     }
 }