diff --git a/src/ObjectValidation/ObjectValidation.csproj b/src/ObjectValidation/ObjectValidation.csproj
index d68fe89..d68a09a 100644
--- a/src/ObjectValidation/ObjectValidation.csproj
+++ b/src/ObjectValidation/ObjectValidation.csproj
@@ -22,7 +22,7 @@
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <PackageRequireLicenseAcceptance>True</PackageRequireLicenseAcceptance>
     <PackageReadmeFile>README.md</PackageReadmeFile>
-    <Version>2.5.0</Version>
+    <Version>2.6.1</Version>
     <DebugType>embedded</DebugType>
     <EmbedAllSources>true</EmbedAllSources>
     <Configurations>Debug;Release;Trunk</Configurations>
diff --git a/src/ObjectValidation/RequiredIfAttribute.cs b/src/ObjectValidation/RequiredIfAttribute.cs
index bef90a8..e691737 100644
--- a/src/ObjectValidation/RequiredIfAttribute.cs
+++ b/src/ObjectValidation/RequiredIfAttribute.cs
@@ -12,6 +12,7 @@ namespace wan24.ObjectValidation
     /// <param name="propertyName">Checked property name</param>
     /// <param name="values">Values (one of the value is required in order to match this condition; if not given, the value is required if the checked property has a non-
     /// <see langword="null"/> value)</param>
+    [AttributeUsage(AttributeTargets.All, AllowMultiple = true)]
     public class RequiredIfAttribute(string propertyName, params object?[] values) : RequiredAttribute()
     {
         /// <summary>