diff --git a/DigitalData.Core.Abstractions/Security/ICryptFactory.cs b/DigitalData.Core.Abstractions/Security/ICryptFactory.cs
index 186e919..94c3109 100644
--- a/DigitalData.Core.Abstractions/Security/ICryptFactory.cs
+++ b/DigitalData.Core.Abstractions/Security/ICryptFactory.cs
@@ -30,7 +30,7 @@ namespace DigitalData.Core.Abstractions.Security
         /// <param name="separator">An optional string separator used to separate the issuer and audience. The default is "-_-". It should not be included in the issuer or audience strings.</param>
         /// <returns>A formatted string combining the issuer, audience, and separator, which adheres to valid file naming rules.</returns>
         /// <exception cref="ArgumentException">Thrown when the issuer, audience, or separator contains invalid characters or when the separator is present within the issuer or audience.</exception>
-        Func<string, string, bool, Version?, string, string> RSAKeyNameFormatter { get; }
+        Func<string, string, bool, Version?, string?, string> RSAKeyNameFormatter { get; }
 
         string CreateRSAPrivateKeyPem(int? keySizeInBits = null);
 
diff --git a/DigitalData.Core.Security/CryptFactory.cs b/DigitalData.Core.Security/CryptFactory.cs
index 87212df..d1578e8 100644
--- a/DigitalData.Core.Security/CryptFactory.cs
+++ b/DigitalData.Core.Security/CryptFactory.cs
@@ -10,9 +10,9 @@ namespace DigitalData.Core.Security
 
         public IRSADecryptor this[string key] { get => _decryptors[key]; set => _decryptors[key] = value; }
 
-        public Func<string, string, bool, Version?, string, string> RSAKeyNameFormatter { get; }
+        public Func<string, string, bool, Version?, string?, string> RSAKeyNameFormatter { get; }
 
-        public CryptFactory(ILogger<CryptFactory> logger, IDictionary<string, IRSADecryptor> decryptors, Func<string, string, bool, Version?, string, string> rsaKeyNameFormatter) : base()
+        public CryptFactory(ILogger<CryptFactory> logger, IDictionary<string, IRSADecryptor> decryptors, Func<string, string, bool, Version?, string?, string> rsaKeyNameFormatter) : base()
         {
             _decryptors = decryptors ?? new Dictionary<string, IRSADecryptor>();