diff --git a/Source/ZoomNet/Resources/Roles.cs b/Source/ZoomNet/Resources/Roles.cs
index 69cf64fa..f8efcba0 100644
--- a/Source/ZoomNet/Resources/Roles.cs
+++ b/Source/ZoomNet/Resources/Roles.cs
@@ -133,7 +133,7 @@ public Task AssignUsersAsync(string roleId, IEnumerable<string> userIds, Cancell
 			{
 				// Zoom requires either the "id" field or the "email" field.
 				// If both are provided, "id" takes precedence.
-				{ "members", userIds.Select(id => new JsonObject { { (id ?? string.Empty).Contains("@") ? "email" : "id", id } }).ToArray() }
+				{ "members", userIds.Select(id => new JsonObject { { (id ?? string.Empty).Contains('@') ? "email" : "id", id } }).ToArray() }
 			};
 
 			return _client