diff --git a/src/Workleap.ComponentModel.DataAnnotations/GuidAttribute.cs b/src/Workleap.ComponentModel.DataAnnotations/GuidAttribute.cs
index cfe0180..e123c55 100644
--- a/src/Workleap.ComponentModel.DataAnnotations/GuidAttribute.cs
+++ b/src/Workleap.ComponentModel.DataAnnotations/GuidAttribute.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 
@@ -37,8 +37,9 @@ public GuidAttribute(string format)
 
     private bool IsValidGuid(string valueAsString)
     {
+        Guid guid;
         return this.Format is null
-            ? Guid.TryParse(valueAsString, out Guid guid) && this.IsValidGuid(guid)
+            ? Guid.TryParse(valueAsString, out guid) && this.IsValidGuid(guid)
             : Guid.TryParseExact(valueAsString, this.Format, out guid) && this.IsValidGuid(guid);
     }