diff --git a/test/-ext-/string/test_ellipsize.rb b/test/-ext-/string/test_ellipsize.rb
index 6ef7d0a1a3..2d066d05b7 100644
--- a/test/-ext-/string/test_ellipsize.rb
+++ b/test/-ext-/string/test_ellipsize.rb
@@ -34,6 +34,7 @@ class Test_StringEllipsize < Test::Unit::TestCase
     a = "\u3042"
     encs = Encoding.list.each do |enc|
       next if enc.dummy?
+      next if enc == Encoding::UTF_16 or enc == Encoding::UTF_32
       begin
         s = a.encode(enc)
         e = "...".encode(enc)