diff --git a/src/Renci.SshNet/PrivateKeyFile.cs b/src/Renci.SshNet/PrivateKeyFile.cs
index 414bcfcd7..495d079d1 100644
--- a/src/Renci.SshNet/PrivateKeyFile.cs
+++ b/src/Renci.SshNet/PrivateKeyFile.cs
@@ -119,7 +119,7 @@ namespace Renci.SshNet
     /// </remarks>
     public partial class PrivateKeyFile : IPrivateKeySource, IDisposable
     {
-        private const string PrivateKeyPattern = @"^-+ *BEGIN (?<keyName>\w+( \w+)*) *-+\r?\n((Proc-Type: 4,ENCRYPTED\r?\nDEK-Info: (?<cipherName>[A-Z0-9-]+),(?<salt>[A-F0-9]+)\r?\n\r?\n)|(Comment: ""?[^\r\n]*""?\r?\n))?(?<data>([a-zA-Z0-9/+=]{1,80}\r?\n)+)(\r?\n)?-+ *END \k<keyName> *-+";
+        private const string PrivateKeyPattern = @"^-+ *BEGIN (?<keyName>\w+( \w+)*) *-+\r?\n((Proc-Type: 4,ENCRYPTED\r?\nDEK-Info: (?<cipherName>[A-Z0-9-]+),(?<salt>[a-fA-F0-9]+)\r?\n\r?\n)|(Comment: ""?[^\r\n]*""?\r?\n))?(?<data>([a-zA-Z0-9/+=]{1,80}\r?\n)+)(\r?\n)?-+ *END \k<keyName> *-+";
         private const string CertificatePattern = @"(?<type>[-\w]+@openssh\.com)\s(?<data>[a-zA-Z0-9\/+=]*)(\s+(?<comment>.*))?";
 
 #if NET7_0_OR_GREATER
diff --git a/test/Renci.SshNet.Tests/Classes/PrivateKeyFileTest.cs b/test/Renci.SshNet.Tests/Classes/PrivateKeyFileTest.cs
index 32dba2cb0..1e5b5f7f9 100644
--- a/test/Renci.SshNet.Tests/Classes/PrivateKeyFileTest.cs
+++ b/test/Renci.SshNet.Tests/Classes/PrivateKeyFileTest.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Text;
 
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -476,6 +477,52 @@ public void Test_Certificate_OPENSSH_ECDSA()
             Assert.AreEqual("ecdsa-sha2-nistp521", algorithms[1].Name);
         }
 
+        [TestMethod]
+        public void Test_LowercaseSalt()
+        {
+            // Occurs occasionally in keys generated from older BouncyCastle versions
+
+            string pk = """
+            -----BEGIN RSA PRIVATE KEY-----
+            Proc-Type: 4,ENCRYPTED
+            DEK-Info: AES-256-CBC,063de67ae11456c89bce9d4a21be3dfb
+
+            6mS1GhCjAg5mEwMFcKRJwg1uxCeY3ekJNCQewIN9NSI5A8prBOQ+JSyWAsn6c3Gw
+            OeRyur+5dxMFdt5Hz1CBi9EePvhVyMry7U5U86BWB0HgtDAD02b324sfc6Wk+kj5
+            PZvuKyXDiqdwy0rsbBUT+bLtXjCI4Ws1k/KbbF0OqGhFJJvErNU5x8zMD9mqp92R
+            D8ZZ/F8Sks3V/JeUisAF86sgMfVCELJobn5Zq/IaUyzQwC6IEL+Sy5fSBB5NHiex
+            NDIJg2RW79uLbufCpuoMPS/GKydf4dq0L5MwvKeqtUgf9Wddc+ZAE4+q1Xz/T8iN
+            3IMqsQfVbYjVK7uTaVGKH+Ew77Qryj01Vg+zyzdf4UwOV3XXQKLVCjNxpMCVtoq7
+            S45M3Ad7598vb7ooa/BFCIcEM8TkuzPnuttLqjzXEzUcA5kqm3kV14IKtlexBfNT
+            tarbidlZcOinvJaoIT3baP4rVnEWDKcxpc+UzNU5RRty6l0zpRmw/9RQ5+FKreh8
+            eXDHD8TT8ArdaREFM8J2OGpkmIK5sLhhYi9gnTopmKIHn8OAXusmQosEOzS6kGxk
+            aFtZezXSCBGgXp5RsrBGGx3oXWHGuWbEFXAq+M7PKXMQe5rLRv6sQdfTFSB5hgNK
+            82P8UzV1wWtAX4JYAhRh2zA8agY2arbNvbjRyjSbp9HNVBgSbVQ60JInesOqLxEg
+            XURuCYp4F8AeHzyO805MTNpcX7PZT2kOxp9sKKABJ9BJ0RoSWa0LJqXzGCHvrExE
+            g7XY/ZfDFZlPLbQnrOgVlYh7pzyfyKB74/oXHkonAisRfsgnQ87yT2DmcHNP6Cek
+            eae2nrpx2yn9Bf8rYdpmJgNxduO8IZvpn84xEyPqK+FbQsdOefBvsg5TgfzETkh/
+            SJjzbqCTDa3XHEUCInixo/wT7FxT8KR9vk43FGPNVRUvPB2GNxe9ZwLYIir64hcQ
+            CpdA3ipVx4/jVzWQH8KXG9UP9TDAKXEvbndLnr2taPnUdAnznwHN2EkfzS/PrFG4
+            /j3l1+VY2AyRybbCTI2iuwJPnKdxOR5oWW6I2Ksfq93Oy+NQz/zasjyNpCZBZWds
+            5gBmwiNk2Xzq7ikEVtVk3osOQRw/u9GbretfaT9jtClALL3DFbOzL4WxA+0NJqpd
+            NB2MohOJa1BJjdfh6x6EVhugH85Y9uYyz/MQj7piljAJY96190n3Q86b/7phfwuD
+            A/ixS42nqpyOPO+EjiWFerFVTJ3iBj7GXXOZGwCrZfpTbqE7OdTDnE3Vr4MO/Etq
+            kSDmJ/+4SFFh80YwYVERDNFdDxCYxx5AnxaBFwbqjzatTV/btgGVabIf6zm2L6aY
+            BJ5wnBZnRnsRaIMehDQmTjioMcyHBSMqId+LYQp+KFpBXqXQTEjJPnq+t4o2FF/N
+            8yoKR8BX6HXSO5qUndI8emwec1JeveiRai6SDnEz1EFfetYXImR290mlqt0aRjQk
+            t/HXRv+fmDQk5hJbCPICydcVSRyrbzxKkppVceEf9NwkBT1MBsOZIFJ3s3A9I72n
+            XPIab5czlgSLYA/U9nEg2XU21hKD2kRH1OF0WSlpNhN2SJFViVqlC3v36MgHoWNh
+            -----END RSA PRIVATE KEY-----
+            """;
+
+            using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(pk)))
+            {
+                var pkFile = new PrivateKeyFile(stream, "12345");
+
+                TestRsaKeyFile(pkFile);
+            }
+        }
+
         private void SaveStreamToFile(Stream stream, string fileName)
         {
             var buffer = new byte[4000];
@@ -500,6 +547,7 @@ private string GetTempFileName()
 
         private static void TestRsaKeyFile(PrivateKeyFile rsaPrivateKeyFile)
         {
+            Assert.IsInstanceOfType<RsaKey>(rsaPrivateKeyFile.Key);
             Assert.IsNotNull(rsaPrivateKeyFile.HostKeyAlgorithms);
             Assert.AreEqual(3, rsaPrivateKeyFile.HostKeyAlgorithms.Count);