diff --git a/src/SimpleAuthentication.Abstractions/ClaimExtensions.cs b/src/SimpleAuthentication.Abstractions/ClaimExtensions.cs
index e56c257..ee7ca7d 100644
--- a/src/SimpleAuthentication.Abstractions/ClaimExtensions.cs
+++ b/src/SimpleAuthentication.Abstractions/ClaimExtensions.cs
@@ -101,6 +101,15 @@ public static bool HasClaim(this ClaimsPrincipal user, string type)
         return hasClaim;
     }
 
+    /// <summary>
+    /// Adds a collection of string values in the list of claims with the same claim type
+    /// </summary>
+    /// <param name="claims">The claims list</param>
+    /// <param name="type">The type of the claims that will be added</param>
+    /// <param name="values">The collection of values</param>
+    public static IList<Claim> Union(this IList<Claim> claims, string type, IEnumerable<string> values)
+        => claims.Union(values.Select(value => new Claim(type, value))).ToList();
+
     private static T? Convert<T>(string value)
         => (T?)TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(value);
 }