diff --git a/framework/src/Volo.Abp.FluentValidation/Volo.Abp.FluentValidation.csproj b/framework/src/Volo.Abp.FluentValidation/Volo.Abp.FluentValidation.csproj
index af4f5c21c0..2ad46ae78a 100644
--- a/framework/src/Volo.Abp.FluentValidation/Volo.Abp.FluentValidation.csproj
+++ b/framework/src/Volo.Abp.FluentValidation/Volo.Abp.FluentValidation.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.FluentValidation</AssemblyName>
     <PackageId>Volo.Abp.FluentValidation</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/AbpFluentValidationConventionalRegistrar.cs b/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/AbpFluentValidationConventionalRegistrar.cs
index e8d11d0416..5923949b0e 100644
--- a/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/AbpFluentValidationConventionalRegistrar.cs
+++ b/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/AbpFluentValidationConventionalRegistrar.cs
@@ -24,11 +24,11 @@ public class AbpFluentValidationConventionalRegistrar : DefaultConventionalRegis
     {
         return new List<Type>()
             {
-                typeof(IValidator<>).MakeGenericType(GetFirstGenericArgumentOrNull(type, 1))
+                typeof(IValidator<>).MakeGenericType(GetFirstGenericArgumentOrNull(type, 1)!)
             };
     }
 
-    private static Type GetFirstGenericArgumentOrNull(Type type, int depth)
+    private static Type? GetFirstGenericArgumentOrNull(Type type, int depth)
     {
         const int maxFindDepth = 8;
 
@@ -42,6 +42,6 @@ public class AbpFluentValidationConventionalRegistrar : DefaultConventionalRegis
             return type.GetGenericArguments()[0];
         }
 
-        return GetFirstGenericArgumentOrNull(type.BaseType, depth + 1);
+        return GetFirstGenericArgumentOrNull(type.BaseType!, depth + 1);
     }
 }
diff --git a/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/FluentObjectValidationContributor.cs b/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/FluentObjectValidationContributor.cs
index 596860cffc..b13b393218 100644
--- a/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/FluentObjectValidationContributor.cs
+++ b/framework/src/Volo.Abp.FluentValidation/Volo/Abp/FluentValidation/FluentObjectValidationContributor.cs
@@ -29,7 +29,7 @@ public class FluentObjectValidationContributor : IObjectValidationContributor, I
 
         var result = await validator.ValidateAsync((IValidationContext)Activator.CreateInstance(
             typeof(ValidationContext<>).MakeGenericType(context.ValidatingObject.GetType()),
-            context.ValidatingObject));
+            context.ValidatingObject)!);
 
         if (!result.IsValid)
         {