IEnumerable Null Check

ExtMethod.cs

public static class IEnumerableExtensions
{
  public static IEnumerable<T> EmptyIfNull<T>(this IEnumerable<T> source)
  {
    return source ?? Enumerable.Empty<T>();
  }
}

Usage.cs

foreach (var item in items.EmptyIfNull())
{
  //do something
}

I'm surprised that the pseudo-monad of IEnumerable doesn't already implement this Maybe-ish behavior.