diff --git a/Models/Validation/FileTypeAttr.cs b/Models/Validation/FileTypeAttr.cs
index a376d4a..3998c05 100644
--- a/Models/Validation/FileTypeAttr.cs
+++ b/Models/Validation/FileTypeAttr.cs
@@ -7,6 +7,7 @@ using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 
 namespace pwt_0x01_ng.Models.Validation
 {
+	[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property | AttributeTargets.Parameter, AllowMultiple = false)]
 	public class FileTypeAttr : ValidationAttribute, IClientModelValidator
 	{
 		private readonly string type;