diff --git a/Pilz.Cryptography/SecureString.cs b/Pilz.Cryptography/SecureString.cs
index e037c26..54654c5 100644
--- a/Pilz.Cryptography/SecureString.cs
+++ b/Pilz.Cryptography/SecureString.cs
@@ -70,7 +70,7 @@ namespace Pilz.Cryptography
             return -2303024 + EqualityComparer<string>.Default.GetHashCode(EncryptedValue);
         }
 
-        public static implicit operator string(SecureString value) => value.Value;
+        public static implicit operator string(SecureString value) => value?.Value;
         public static implicit operator SecureString(string value) => new SecureString(value, false);
 
         public static bool operator ==(SecureString left, SecureString right) => left.EncryptedValue == right.EncryptedValue;