diff --git a/framework/src/Volo.Abp.AutoMapper/AutoMapper/AbpAutoMapperExtensibleDtoExtensions.cs b/framework/src/Volo.Abp.AutoMapper/AutoMapper/AbpAutoMapperExtensibleDtoExtensions.cs
index 5085eecdc2..a564edf18f 100644
--- a/framework/src/Volo.Abp.AutoMapper/AutoMapper/AbpAutoMapperExtensibleDtoExtensions.cs
+++ b/framework/src/Volo.Abp.AutoMapper/AutoMapper/AbpAutoMapperExtensibleDtoExtensions.cs
@@ -10,7 +10,7 @@ public static class AbpAutoMapperExtensibleDtoExtensions
     public static IMappingExpression<TSource, TDestination> MapExtraProperties<TSource, TDestination>(
         this IMappingExpression<TSource, TDestination> mappingExpression,
         MappingPropertyDefinitionChecks? definitionChecks = null,
-        string[] ignoredProperties = null,
+        string[]? ignoredProperties = null,
         bool mapToRegularProperties = false)
         where TDestination : IHasExtraProperties
         where TSource : IHasExtraProperties
diff --git a/framework/src/Volo.Abp.AutoMapper/Volo.Abp.AutoMapper.csproj b/framework/src/Volo.Abp.AutoMapper/Volo.Abp.AutoMapper.csproj
index f1408e38e2..e5c78948ba 100644
--- a/framework/src/Volo.Abp.AutoMapper/Volo.Abp.AutoMapper.csproj
+++ b/framework/src/Volo.Abp.AutoMapper/Volo.Abp.AutoMapper.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.1</TargetFramework>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.AutoMapper</AssemblyName>
     <PackageId>Volo.Abp.AutoMapper</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.AutoMapper/Volo/Abp/AutoMapper/MapperAccessor.cs b/framework/src/Volo.Abp.AutoMapper/Volo/Abp/AutoMapper/MapperAccessor.cs
index 7e2f94819f..5751180185 100644
--- a/framework/src/Volo.Abp.AutoMapper/Volo/Abp/AutoMapper/MapperAccessor.cs
+++ b/framework/src/Volo.Abp.AutoMapper/Volo/Abp/AutoMapper/MapperAccessor.cs
@@ -4,5 +4,5 @@ namespace Volo.Abp.AutoMapper;
 
 internal class MapperAccessor : IMapperAccessor
 {
-    public IMapper Mapper { get; set; }
+    public IMapper Mapper { get; set; } = default!;
 }