diff --git a/Libraries/SPTarkov.Server.Core/Utils/JsonUtil.cs b/Libraries/SPTarkov.Server.Core/Utils/JsonUtil.cs
index 4f3aefb0..94f16e6a 100644
--- a/Libraries/SPTarkov.Server.Core/Utils/JsonUtil.cs
+++ b/Libraries/SPTarkov.Server.Core/Utils/JsonUtil.cs
@@ -11,6 +11,7 @@ public class JsonUtil
 {
     private static JsonSerializerOptions? jsonSerializerOptionsNoIndent;
     private static JsonSerializerOptions? jsonSerializerOptionsIndented;
+    private static readonly Lock _lock = new();
 
     public JsonUtil(
         IEnumerable<IJsonConverterRegistrator> registrators
@@ -28,14 +29,20 @@ public class JsonUtil
         {
             foreach (var converter in registrator.GetJsonConverters())
             {
-                jsonSerializerOptionsNoIndent.Converters.Add(converter);
+                lock (_lock)
+                {
+                    jsonSerializerOptionsNoIndent.Converters.Add(converter);
+                }
             }
         }
 
-        jsonSerializerOptionsIndented = new JsonSerializerOptions(jsonSerializerOptionsNoIndent)
+        lock (_lock)
         {
-            WriteIndented = true
-        };
+            jsonSerializerOptionsIndented = new JsonSerializerOptions(jsonSerializerOptionsNoIndent)
+            {
+                WriteIndented = true
+            };
+        }
     }
 
     /// <summary>
diff --git a/Libraries/SPTarkov.Server.Core/Utils/RandomUtil.cs b/Libraries/SPTarkov.Server.Core/Utils/RandomUtil.cs
index d9e4f112..4643ba43 100644
--- a/Libraries/SPTarkov.Server.Core/Utils/RandomUtil.cs
+++ b/Libraries/SPTarkov.Server.Core/Utils/RandomUtil.cs
@@ -400,7 +400,7 @@ public class RandomUtil(ISptLogger<RandomUtil> _logger, ICloner _cloner)
 
         while (currentIndex != 0)
         {
-            var randomIndex = GetInt(0, currentIndex);
+            var randomIndex = GetInt(0, currentIndex, true);
             currentIndex--;
 
             // Swap it with the current element.
diff --git a/UnitTests/DI.cs b/UnitTests/DI.cs
new file mode 100644
index 00000000..5c032824
--- /dev/null
+++ b/UnitTests/DI.cs
@@ -0,0 +1,39 @@
+using Microsoft.Extensions.DependencyInjection;
+using SPTarkov.Server.Core.Models.Utils;
+using SPTarkov.Server.Core.Utils;
+using SPTarkov.Server.Core.Utils.Cloners;
+using SPTarkov.Server.Core.Utils.Json.Converters;
+using UnitTests.Mock;
+
+namespace UnitTests;
+
+public class DI
+{
+    private static IServiceProvider _serviceProvider;
+
+    private static IServiceProvider ConfigureServices()
+    {
+        if (_serviceProvider != null)
+        {
+            return _serviceProvider;
+        }
+
+        var services = new ServiceCollection();
+        var jsonUtil = new JsonUtil([ new SptJsonConverterRegistrator() ]);
+        var mathUtil = new MathUtil();
+
+        services.AddSingleton<JsonUtil>(jsonUtil);
+        services.AddSingleton<MathUtil>(mathUtil);
+        services.AddSingleton<ICloner,JsonCloner>();
+        services.AddSingleton<ISptLogger<RandomUtil>,MockLogger<RandomUtil>>();
+        services.AddSingleton<RandomUtil>();
+        services.AddSingleton<HashUtil>();
+
+        return _serviceProvider = services.BuildServiceProvider();
+    }
+
+    public static T GetService<T>() where T : notnull
+    {
+        return ConfigureServices().GetRequiredService<T>();
+    }
+}
diff --git a/UnitTests/Tests/Utils/HashUtilTests.cs b/UnitTests/Tests/Utils/HashUtilTests.cs
index 9d15bc49..de9c21ad 100644
--- a/UnitTests/Tests/Utils/HashUtilTests.cs
+++ b/UnitTests/Tests/Utils/HashUtilTests.cs
@@ -1,16 +1,19 @@
 using System.Collections.Concurrent;
 using System.Diagnostics;
 using SPTarkov.Server.Core.Utils;
-using SPTarkov.Server.Core.Utils.Cloners;
-using SPTarkov.Server.Core.Utils.Json.Converters;
-using UnitTests.Mock;
 
 namespace UnitTests.Tests.Utils;
 
 [TestClass]
 public class HashUtilTests
 {
-    protected HashUtil _hashUtil = new(new RandomUtil(new MockLogger<RandomUtil>(), new JsonCloner(new JsonUtil([ new SptJsonConverterRegistrator() ]))));
+    private HashUtil _hashUtil;
+
+    [TestInitialize]
+    public void Initialize()
+    {
+        _hashUtil = DI.GetService<HashUtil>();
+    }
 
     [TestMethod]
     public void GenerateTest()
diff --git a/UnitTests/Tests/Utils/JsonUtilTests.cs b/UnitTests/Tests/Utils/JsonUtilTests.cs
index 8df9406a..d74cc86b 100644
--- a/UnitTests/Tests/Utils/JsonUtilTests.cs
+++ b/UnitTests/Tests/Utils/JsonUtilTests.cs
@@ -1,13 +1,18 @@
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Utils;
-using SPTarkov.Server.Core.Utils.Json.Converters;
 
 namespace UnitTests.Tests.Utils;
 
 [TestClass]
 public class JsonUtilTests
 {
-    protected JsonUtil _jsonUtil = new([ new SptJsonConverterRegistrator() ]);
+    private JsonUtil _jsonUtil;
+
+    [TestInitialize]
+    public void Initialize()
+    {
+        _jsonUtil = DI.GetService<JsonUtil>();
+    }
 
     [TestMethod]
     public void SerializeAndDeserialize_WithDictionaryOfETFEnum_ExpectCorrectParsing()
diff --git a/UnitTests/Tests/Utils/MathUtilTests.cs b/UnitTests/Tests/Utils/MathUtilTests.cs
index f9f99c07..41ebeb52 100644
--- a/UnitTests/Tests/Utils/MathUtilTests.cs
+++ b/UnitTests/Tests/Utils/MathUtilTests.cs
@@ -5,7 +5,13 @@ namespace UnitTests.Tests.Utils;
 [TestClass]
 public class MathUtilTests
 {
-    protected MathUtil _mathUtil = new();
+    private MathUtil _mathUtil;
+
+    [TestInitialize]
+    public void Initialize()
+    {
+        _mathUtil = DI.GetService<MathUtil>();
+    }
 
     [TestMethod]
     public void ListSumTest()
diff --git a/UnitTests/Tests/Utils/RandomUtilTests.cs b/UnitTests/Tests/Utils/RandomUtilTests.cs
index 1442e199..89985d3d 100644
--- a/UnitTests/Tests/Utils/RandomUtilTests.cs
+++ b/UnitTests/Tests/Utils/RandomUtilTests.cs
@@ -1,14 +1,17 @@
 using SPTarkov.Server.Core.Utils;
-using SPTarkov.Server.Core.Utils.Cloners;
-using SPTarkov.Server.Core.Utils.Json.Converters;
-using UnitTests.Mock;
 
 namespace UnitTests.Tests.Utils;
 
 [TestClass]
 public sealed class RandomUtilTests
 {
-    private readonly RandomUtil _randomUtil = new(new MockLogger<RandomUtil>(), new JsonCloner(new JsonUtil([ new SptJsonConverterRegistrator() ])));
+    private RandomUtil _randomUtil;
+
+    [TestInitialize]
+    public void Initialize()
+    {
+        _randomUtil = DI.GetService<RandomUtil>();
+    }
 
     [TestMethod]
     public void GetIntTest()