diff --git a/src/SampSharp.MapObjects.Tests/MapObjectServiceTests.cs b/src/SampSharp.MapObjects.Tests/MapObjectServiceTests.cs
index 25d3027..bbf238d 100644
--- a/src/SampSharp.MapObjects.Tests/MapObjectServiceTests.cs
+++ b/src/SampSharp.MapObjects.Tests/MapObjectServiceTests.cs
@@ -3,7 +3,6 @@
 public class MapObjectServiceTests
 {
     private FakeMapContext _fakeMapContext;
-    private Dictionary<string, MapDefinition> _maps;
 
     [SetUp]
     public void Init()
@@ -13,15 +12,13 @@ public void Init()
             Substitute.For<IOmpEntityProvider>(),
             NullLogger<MapContext>.Instance
         );
-
-        _maps = [];
     }
 
     [Test]
     public void Load_WhenMapNameIsNull_ShouldThrowArgumentNullException()
     {
         // Arrange
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps());
 
         // Act
         Action act = () => mapObjects.Load(null!);
@@ -34,7 +31,7 @@ public void Load_WhenMapNameIsNull_ShouldThrowArgumentNullException()
     public void Load_WhenMapNameIsEmpty_ShouldThrowArgumentException()
     {
         // Arrange
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps());
 
         // Act
         Action act = () => mapObjects.Load(string.Empty);
@@ -47,7 +44,7 @@ public void Load_WhenMapNameIsEmpty_ShouldThrowArgumentException()
     public void Load_WhenMapIsNotRegistered_ShouldDoNothing()
     {
         // Arrange
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps());
 
         // Act
         Action act = () => mapObjects.Load("Unknown");
@@ -61,9 +58,7 @@ public void Load_WhenMapIsRegistered_ShouldLoadMap()
     {
         // Arrange
         TestMapDefinition map = new("Map");
-        _maps.Add(map.Name, map);
-
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps(map));
 
         // Act
         mapObjects.Load(map.Name);
@@ -78,11 +73,7 @@ public void Load_WhenAnotherMapIsAlreadyLoaded_ShouldThrowInvalidOperationExcept
         // Arrange
         TestMapDefinition map1 = new("Map1");
         TestMapDefinition map2 = new("Map2");
-
-        _maps.Add(map1.Name, map1);
-        _maps.Add(map2.Name, map2);
-
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps(map1, map2));
         mapObjects.Load(map1.Name);
 
         // Act
@@ -96,7 +87,7 @@ public void Load_WhenAnotherMapIsAlreadyLoaded_ShouldThrowInvalidOperationExcept
     public void Unload_WhenNoMapIsLoaded_ShouldThrowInvalidOperationException()
     {
         // Arrange
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps());
 
         // Act
         Action act = mapObjects.Unload;
@@ -110,9 +101,7 @@ public void Unload_WhenMapIsLoaded_ShouldUnloadMap()
     {
         // Arrange
         TestMapDefinition map = new("Map");
-        _maps.Add(map.Name, map);
-
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps(map));
         mapObjects.Load(map.Name);
 
         // Act
@@ -129,11 +118,7 @@ public void Unload_WhenMapWasUnloaded_ShouldAllowLoadingAnotherMap()
         // Arrange
         TestMapDefinition map1 = new("Map1");
         TestMapDefinition map2 = new("Map2");
-
-        _maps.Add(map1.Name, map1);
-        _maps.Add(map2.Name, map2);
-
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps(map1, map2));
         mapObjects.Load(map1.Name);
         mapObjects.Unload();
 
@@ -153,13 +138,8 @@ public void Unload_WhenOnUnloadThrows_ShouldAllowLoadingAnotherMap()
         {
             ThrowOnUnload = true
         };
-
         TestMapDefinition map2 = new("Map2");
-
-        _maps.Add(map1.Name, map1);
-        _maps.Add(map2.Name, map2);
-
-        MapObjectService mapObjects = new(_fakeMapContext, _maps);
+        MapObjectService mapObjects = new(_fakeMapContext, CreateMaps(map1, map2));
         mapObjects.Load(map1.Name);
 
         // Act
@@ -172,4 +152,8 @@ public void Unload_WhenOnUnloadThrows_ShouldAllowLoadingAnotherMap()
         load.Should().NotThrow();
         map2.WasLoaded.Should().BeTrue();
     }
+
+    private static FrozenDictionary<string, MapDefinition> CreateMaps(
+        params MapDefinition[] maps)
+        => maps.ToFrozenDictionary(m => m.Name);
 }
diff --git a/src/SampSharp.MapObjects.Tests/Usings.cs b/src/SampSharp.MapObjects.Tests/Usings.cs
index 1cd0943..48f7202 100644
--- a/src/SampSharp.MapObjects.Tests/Usings.cs
+++ b/src/SampSharp.MapObjects.Tests/Usings.cs
@@ -1,4 +1,5 @@
 global using System.Numerics;
+global using System.Collections.Frozen;
 global using NUnit.Framework;
 global using FluentAssertions;
 global using NSubstitute;
diff --git a/src/SampSharp.MapObjects/MapObjectService.cs b/src/SampSharp.MapObjects/MapObjectService.cs
index 4e95186..948fe0c 100644
--- a/src/SampSharp.MapObjects/MapObjectService.cs
+++ b/src/SampSharp.MapObjects/MapObjectService.cs
@@ -2,7 +2,7 @@
 
 internal sealed class MapObjectService(
     MapContext mapContext,
-    Dictionary<string, MapDefinition> maps) : IMapObjectService
+    FrozenDictionary<string, MapDefinition> maps) : IMapObjectService
 {
     private MapDefinition _loadedMap;
 
diff --git a/src/SampSharp.MapObjects/ServiceCollectionExtensions.cs b/src/SampSharp.MapObjects/ServiceCollectionExtensions.cs
index 0995200..20a3929 100644
--- a/src/SampSharp.MapObjects/ServiceCollectionExtensions.cs
+++ b/src/SampSharp.MapObjects/ServiceCollectionExtensions.cs
@@ -59,7 +59,7 @@ public static IServiceCollection AddMapObjects(this IServiceCollection services)
             .AddSingleton(sp =>
             {
                 IEnumerable<MapDefinition> maps = sp.GetRequiredService<IEnumerable<MapDefinition>>();
-                return maps.ToDictionary(map => map.Name);
+                return maps.ToFrozenDictionary(map => map.Name);
             })
             .AddSingleton<IMapObjectService, MapObjectService>()
             .AddSingleton<MapContext>()
diff --git a/src/SampSharp.MapObjects/Usings.cs b/src/SampSharp.MapObjects/Usings.cs
index 3015407..af9bbce 100644
--- a/src/SampSharp.MapObjects/Usings.cs
+++ b/src/SampSharp.MapObjects/Usings.cs
@@ -1,4 +1,5 @@
 global using System.Numerics;
+global using System.Collections.Frozen;
 global using Microsoft.Extensions.Logging;
 global using Microsoft.Extensions.DependencyInjection;
 global using SampSharp.Entities;