diff --git a/Directory.Build.props b/Directory.Build.props
index b3dfa48..d46f690 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,5 +1,5 @@
 <Project>
     <PropertyGroup>
-        <Version>2.4.0</Version>
+        <Version>2.4.1</Version>
     </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/TakasakiStudio.Lina.Common/Extensions/RuleBuilderExtension.cs b/TakasakiStudio.Lina.Common/Extensions/RuleBuilderExtension.cs
index 24f75b7..8e7875a 100644
--- a/TakasakiStudio.Lina.Common/Extensions/RuleBuilderExtension.cs
+++ b/TakasakiStudio.Lina.Common/Extensions/RuleBuilderExtension.cs
@@ -18,8 +18,11 @@ public static IRuleBuilderOptions<T, string> IsCpf<T>(
         return ruleBuilder.Must(BeAValidCpf);
     }
 
-    public static bool BeAValidCpf(string input)
+    public static bool BeAValidCpf(string? input)
     {
+        if (string.IsNullOrWhiteSpace(input))
+            return false;
+        
         var numbers = ToNumbers(input);
         if (numbers.Length != 11 || numbers.Distinct().Count() == 1)
             return false;
@@ -43,8 +46,11 @@ public static bool BeAValidCpf(string input)
         return numbers[9] == v1 && numbers[10] == v2;
     }
 
-    public static bool BeAValidCnpj(string input)
+    public static bool BeAValidCnpj(string? input)
     {
+        if (string.IsNullOrWhiteSpace(input))
+            return false;
+        
         var numbers = ToNumbers(input);
         if (numbers.Length != 14)
             return false;