diff --git a/DepotDownloader/ProtoManifest.cs b/DepotDownloader/ProtoManifest.cs
index 70389a0..1770cb5 100644
--- a/DepotDownloader/ProtoManifest.cs
+++ b/DepotDownloader/ProtoManifest.cs
@@ -1,7 +1,8 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Compression;
+using System.Security.Cryptography;
 using ProtoBuf;
 using SteamKit2;
 
@@ -135,7 +136,7 @@ namespace DepotDownloader
                 using (var ds = new DeflateStream(fs, CompressionMode.Decompress))
                     ds.CopyTo(ms);
 
-                checksum = Util.SHAHash(ms.ToArray());
+                checksum = SHA1.HashData(ms.ToArray());
 
                 ms.Seek(0, SeekOrigin.Begin);
                 return Serializer.Deserialize<ProtoManifest>(ms);
@@ -148,7 +149,7 @@ namespace DepotDownloader
             {
                 Serializer.Serialize(ms, this);
 
-                checksum = Util.SHAHash(ms.ToArray());
+                checksum = SHA1.HashData(ms.ToArray());
 
                 ms.Seek(0, SeekOrigin.Begin);
 
diff --git a/DepotDownloader/Steam3Session.cs b/DepotDownloader/Steam3Session.cs
index 40adc9d..b1495fe 100644
--- a/DepotDownloader/Steam3Session.cs
+++ b/DepotDownloader/Steam3Session.cs
@@ -560,8 +560,14 @@ namespace DepotDownloader
                         logonDetails.Password = null;
                         logonDetails.AccessToken = result.RefreshToken;
 
-                        // Should i check if guardData is null ?
-                        AccountSettingsStore.Instance.GuardData[result.AccountName] = result.NewGuardData;
+                        if (result.NewGuardData != null)
+                        {
+                            AccountSettingsStore.Instance.GuardData[result.AccountName] = result.NewGuardData;
+                        }
+                        else
+                        {
+                            AccountSettingsStore.Instance.GuardData.Remove(result.AccountName);
+                        }
                         AccountSettingsStore.Instance.LoginTokens[result.AccountName] = result.RefreshToken;
                         AccountSettingsStore.Save();
                     }
diff --git a/DepotDownloader/Util.cs b/DepotDownloader/Util.cs
index 9dd954c..eccca48 100644
--- a/DepotDownloader/Util.cs
+++ b/DepotDownloader/Util.cs
@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
-using System.Security.Cryptography;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -113,13 +112,6 @@ namespace DepotDownloader
             return BitConverter.GetBytes(a | (b << 16));
         }
 
-        public static byte[] SHAHash(byte[] input)
-        {
-            var output = SHA1.HashData(input);
-
-            return output;
-        }
-
         public static byte[] DecodeHexString(string hex)
         {
             if (hex == null)
@@ -144,7 +136,7 @@ namespace DepotDownloader
         public static async Task InvokeAsync(IEnumerable<Func<Task>> taskFactories, int maxDegreeOfParallelism)
         {
             ArgumentNullException.ThrowIfNull(taskFactories);
-            if (maxDegreeOfParallelism <= 0) throw new ArgumentException(nameof(maxDegreeOfParallelism));
+            ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(0, maxDegreeOfParallelism);
 
             var queue = taskFactories.ToArray();