diff --git a/src/SharpCompress/Common/Rar/RarEntry.cs b/src/SharpCompress/Common/Rar/RarEntry.cs
index f3614a40..7f280e4a 100644
--- a/src/SharpCompress/Common/Rar/RarEntry.cs
+++ b/src/SharpCompress/Common/Rar/RarEntry.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using SharpCompress.Common.Rar.Headers;
 
 namespace SharpCompress.Common.Rar;
@@ -11,7 +11,8 @@ public abstract class RarEntry : Entry
     /// As the V2017 port isn't complete, add this check to use the legacy Rar code.
     /// </summary>
     internal bool IsRarV3 =>
-        FileHeader.CompressionAlgorithm == 20
+        FileHeader.CompressionAlgorithm == 15
+        || FileHeader.CompressionAlgorithm == 20
         || FileHeader.CompressionAlgorithm == 26
         || FileHeader.CompressionAlgorithm == 29
         || FileHeader.CompressionAlgorithm == 36; //Nanook - Added 20+26 as Test arc from WinRar2.8 (algo 20) was failing with 2017 code
diff --git a/tests/SharpCompress.Test/Rar/RarArchiveTests.cs b/tests/SharpCompress.Test/Rar/RarArchiveTests.cs
index 0936a8ed..1e345150 100644
--- a/tests/SharpCompress.Test/Rar/RarArchiveTests.cs
+++ b/tests/SharpCompress.Test/Rar/RarArchiveTests.cs
@@ -355,6 +355,22 @@ public class RarArchiveTests : ArchiveTests
     [Fact]
     public void Rar2_ArchiveFileRead() => ArchiveFileRead("Rar2.rar");
 
+    [Fact]
+    public void Rar15_ArchiveFileRead()
+    {
+        UseExtensionInsteadOfNameToVerify = true;
+        UseCaseInsensitiveToVerify= true;
+        ArchiveFileRead("Rar15.rar");
+    }
+    [Fact]
+    public void Rar15_ArchiveVersionTest()
+    {
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, "Rar15.rar");
+
+        using var archive = RarArchive.Open(testArchive);
+        Assert.Equal(1, archive.MinVersion);
+        Assert.Equal(1, archive.MaxVersion);
+    }
     [Fact]
     public void Rar2_ArchiveVersionTest()
     {
diff --git a/tests/SharpCompress.Test/TestBase.cs b/tests/SharpCompress.Test/TestBase.cs
index ddfd0096..3ad1fe79 100644
--- a/tests/SharpCompress.Test/TestBase.cs
+++ b/tests/SharpCompress.Test/TestBase.cs
@@ -138,12 +138,23 @@ public class TestBase : IDisposable
     }
 
     protected bool UseExtensionInsteadOfNameToVerify { get; set; }
+    protected bool UseCaseInsensitiveToVerify { get; set; }
 
     protected void VerifyFilesByExtension()
     {
-        var extracted = Directory
-            .EnumerateFiles(SCRATCH_FILES_PATH, "*.*", SearchOption.AllDirectories)
-            .ToLookup(path => Path.GetExtension(path));
+        ILookup<string, string> extracted;
+        if (UseCaseInsensitiveToVerify)
+        {
+            extracted = Directory
+                .EnumerateFiles(SCRATCH_FILES_PATH, "*.*", SearchOption.AllDirectories)
+                .ToLookup(path => Path.GetExtension(path).ToLowerInvariant());
+        }
+        else
+        {
+            extracted = Directory
+                .EnumerateFiles(SCRATCH_FILES_PATH, "*.*", SearchOption.AllDirectories)
+                .ToLookup(path => Path.GetExtension(path));
+        }
         var original = Directory
             .EnumerateFiles(ORIGINAL_FILES_PATH, "*.*", SearchOption.AllDirectories)
             .ToLookup(path => Path.GetExtension(path));
diff --git a/tests/TestArchives/Archives/Rar15.rar b/tests/TestArchives/Archives/Rar15.rar
new file mode 100644
index 00000000..dfd42bf0
Binary files /dev/null and b/tests/TestArchives/Archives/Rar15.rar differ