diff --git a/Jellyfin.Server.Implementations/Activity/ActivityManager.cs b/Jellyfin.Server.Implementations/Activity/ActivityManager.cs
index 7bde4f35b..27360afb0 100644
--- a/Jellyfin.Server.Implementations/Activity/ActivityManager.cs
+++ b/Jellyfin.Server.Implementations/Activity/ActivityManager.cs
@@ -27,7 +27,7 @@ namespace Jellyfin.Server.Implementations.Activity
         }
 
         /// <inheritdoc/>
-        public event EventHandler<GenericEventArgs<ActivityLogEntry>> EntryCreated;
+        public event EventHandler<GenericEventArgs<ActivityLogEntry>>? EntryCreated;
 
         /// <inheritdoc/>
         public async Task CreateAsync(ActivityLog entry)
diff --git a/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStartLogger.cs b/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStartLogger.cs
index ec4a76e7f..0340248bb 100644
--- a/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStartLogger.cs
+++ b/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStartLogger.cs
@@ -86,7 +86,7 @@ namespace Jellyfin.Server.Implementations.Events.Consumers.Session
             return name;
         }
 
-        private static string GetPlaybackNotificationType(string mediaType)
+        private static string? GetPlaybackNotificationType(string mediaType)
         {
             if (string.Equals(mediaType, MediaType.Audio, StringComparison.OrdinalIgnoreCase))
             {
diff --git a/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStopLogger.cs b/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStopLogger.cs
index a0bad29e9..1648b1b47 100644
--- a/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStopLogger.cs
+++ b/Jellyfin.Server.Implementations/Events/Consumers/Session/PlaybackStopLogger.cs
@@ -94,7 +94,7 @@ namespace Jellyfin.Server.Implementations.Events.Consumers.Session
             return name;
         }
 
-        private static string GetPlaybackStoppedNotificationType(string mediaType)
+        private static string? GetPlaybackStoppedNotificationType(string mediaType)
         {
             if (string.Equals(mediaType, MediaType.Audio, StringComparison.OrdinalIgnoreCase))
             {
diff --git a/Jellyfin.Server.Implementations/Jellyfin.Server.Implementations.csproj b/Jellyfin.Server.Implementations/Jellyfin.Server.Implementations.csproj
index 5f508ea0a..9e4a2065f 100644
--- a/Jellyfin.Server.Implementations/Jellyfin.Server.Implementations.csproj
+++ b/Jellyfin.Server.Implementations/Jellyfin.Server.Implementations.csproj
@@ -5,6 +5,7 @@
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
diff --git a/Jellyfin.Server.Implementations/JellyfinDb.cs b/Jellyfin.Server.Implementations/JellyfinDb.cs
index 7f3f83749..39f842354 100644
--- a/Jellyfin.Server.Implementations/JellyfinDb.cs
+++ b/Jellyfin.Server.Implementations/JellyfinDb.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
diff --git a/Jellyfin.Server.Implementations/Users/DefaultAuthenticationProvider.cs b/Jellyfin.Server.Implementations/Users/DefaultAuthenticationProvider.cs
index 662b4bf65..6a78e7ee6 100644
--- a/Jellyfin.Server.Implementations/Users/DefaultAuthenticationProvider.cs
+++ b/Jellyfin.Server.Implementations/Users/DefaultAuthenticationProvider.cs
@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Linq;
 using System.Text;
diff --git a/Jellyfin.Server.Implementations/Users/DefaultPasswordResetProvider.cs b/Jellyfin.Server.Implementations/Users/DefaultPasswordResetProvider.cs
index 334f27f85..9cc1c3e5e 100644
--- a/Jellyfin.Server.Implementations/Users/DefaultPasswordResetProvider.cs
+++ b/Jellyfin.Server.Implementations/Users/DefaultPasswordResetProvider.cs
@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.IO;
diff --git a/Jellyfin.Server.Implementations/Users/DeviceAccessEntryPoint.cs b/Jellyfin.Server.Implementations/Users/DeviceAccessEntryPoint.cs
index 1fb89c4a6..dbba80c21 100644
--- a/Jellyfin.Server.Implementations/Users/DeviceAccessEntryPoint.cs
+++ b/Jellyfin.Server.Implementations/Users/DeviceAccessEntryPoint.cs
@@ -1,5 +1,4 @@
-#nullable enable
-#pragma warning disable CS1591
+#pragma warning disable CS1591
 
 using System.Threading.Tasks;
 using Jellyfin.Data.Entities;
diff --git a/Jellyfin.Server.Implementations/Users/InvalidAuthProvider.cs b/Jellyfin.Server.Implementations/Users/InvalidAuthProvider.cs
index 5f32479e1..c4e4c460a 100644
--- a/Jellyfin.Server.Implementations/Users/InvalidAuthProvider.cs
+++ b/Jellyfin.Server.Implementations/Users/InvalidAuthProvider.cs
@@ -1,5 +1,3 @@
-#nullable enable
-
 using System.Threading.Tasks;
 using Jellyfin.Data.Entities;
 using MediaBrowser.Controller.Authentication;
diff --git a/Jellyfin.Server.Implementations/Users/UserManager.cs b/Jellyfin.Server.Implementations/Users/UserManager.cs
index e37fcc908..b76b272cf 100644
--- a/Jellyfin.Server.Implementations/Users/UserManager.cs
+++ b/Jellyfin.Server.Implementations/Users/UserManager.cs
@@ -1,5 +1,4 @@
-#nullable enable
-#pragma warning disable CA1307
+#pragma warning disable CA1307
 
 using System;
 using System.Collections.Concurrent;
diff --git a/Jellyfin.Server.Implementations/ValueConverters/DateTimeKindValueConverter.cs b/Jellyfin.Server.Implementations/ValueConverters/DateTimeKindValueConverter.cs
index 8a510898b..a9a18c823 100644
--- a/Jellyfin.Server.Implementations/ValueConverters/DateTimeKindValueConverter.cs
+++ b/Jellyfin.Server.Implementations/ValueConverters/DateTimeKindValueConverter.cs
@@ -13,9 +13,9 @@ namespace Jellyfin.Server.Implementations.ValueConverters
         /// </summary>
         /// <param name="kind">The kind to specify.</param>
         /// <param name="mappingHints">The mapping hints.</param>
-        public DateTimeKindValueConverter(DateTimeKind kind, ConverterMappingHints mappingHints = null)
+        public DateTimeKindValueConverter(DateTimeKind kind, ConverterMappingHints? mappingHints = null)
             : base(v => v.ToUniversalTime(), v => DateTime.SpecifyKind(v, kind), mappingHints)
         {
         }
     }
-}
\ No newline at end of file
+}