diff --git a/Directory.Packages.props b/Directory.Packages.props
index 432be66..a6d52bc 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -38,8 +38,8 @@
     <PackageVersion Include="Serilog.Sinks.Console" Version="6.1.1" />
     <PackageVersion Include="Serilog.Sinks.File" Version="7.0.0" />
     <PackageVersion Include="Shouldly" Version="4.3.0" />
-    <PackageVersion Include="SSH.NET" Version="2025.1.0" />
-    <PackageVersion Include="SshNet.Keygen" Version="2024.2.0.2" />
+    <PackageVersion Include="SSH.NET" Version="2026.0.0" />
+    <PackageVersion Include="SshNet.Keygen" Version="2026.0.0" />
     <PackageVersion Include="SshNet.PuttyKeyFile" Version="2024.2.0.3" />
     <PackageVersion Include="Svg.Controls.Skia.Avalonia" Version="12.0.0.13" />
     <PackageVersion Include="System.Interactive" Version="7.0.1" />
diff --git a/OpenSSH_GUI.Tests/Core/Lib/Keys/PuttyKeyFileCompatibilityTests.cs b/OpenSSH_GUI.Tests/Core/Lib/Keys/PuttyKeyFileCompatibilityTests.cs
new file mode 100644
index 0000000..f182f82
--- /dev/null
+++ b/OpenSSH_GUI.Tests/Core/Lib/Keys/PuttyKeyFileCompatibilityTests.cs
@@ -0,0 +1,46 @@
+using Renci.SshNet;
+using Shouldly;
+using SshNet.Keygen;
+using SshNet.Keygen.Extensions;
+using SshNet.Keygen.SshKeyEncryption;
+using Xunit;
+
+namespace OpenSSH_GUI.Tests.Core.Lib.Keys;
+
+/// <summary>
+///     Guards the PPK round trip across SSH.NET and SshNet.Keygen upgrades: keys written by SshNet.Keygen in PuTTY format
+///     must load with SSH.NET's <see cref="PrivateKeyFile" />, which is how the app opens <c>.ppk</c> files.
+/// </summary>
+public sealed class PuttyKeyFileCompatibilityTests : IDisposable
+{
+    private readonly string directory = Directory.CreateTempSubdirectory("putty-compat").FullName;
+
+    public void Dispose() { Directory.Delete(directory, true); }
+
+    [Theory]
+    [InlineData(SshKeyType.RSA, SshKeyFormat.PuTTYv2, null)]
+    [InlineData(SshKeyType.RSA, SshKeyFormat.PuTTYv3, null)]
+    [InlineData(SshKeyType.ED25519, SshKeyFormat.PuTTYv2, null)]
+    [InlineData(SshKeyType.ED25519, SshKeyFormat.PuTTYv3, null)]
+    [InlineData(SshKeyType.ECDSA, SshKeyFormat.PuTTYv3, null)]
+    [InlineData(SshKeyType.RSA, SshKeyFormat.PuTTYv2, "ppk-passphrase")]
+    [InlineData(SshKeyType.ED25519, SshKeyFormat.PuTTYv3, "ppk-passphrase")]
+    [InlineData(SshKeyType.ECDSA, SshKeyFormat.PuTTYv3, "ppk-passphrase")]
+    public void PrivateKeyFile_PpkWrittenBySshNetKeygen_LoadsSameKey(SshKeyType keyType, SshKeyFormat format, string? passphrase)
+    {
+        var path = Path.Combine(directory, $"id_{keyType}_{format}.ppk");
+        var info = new SshKeyGenerateInfo(keyType)
+        {
+            Comment = "putty-compat",
+            KeyFormat = format
+        };
+        if (passphrase is not null) info.Encryption = new SshKeyEncryptionAes256(passphrase);
+        var generated = SshKey.Generate(path, FileMode.CreateNew, info);
+
+        using var loaded = passphrase is null ? new PrivateKeyFile(path) : new PrivateKeyFile(path, passphrase);
+
+        GetPublicKeyBlob(loaded).ShouldBe(GetPublicKeyBlob(generated));
+    }
+
+    private static string GetPublicKeyBlob(IPrivateKeySource keySource) => keySource.ToOpenSshPublicFormat().Split(' ')[1];
+}