1 files changed, 9 insertions, 0 deletions
diff --git a/test/-ext-/string/test_fstring.rb b/test/-ext-/string/test_fstring.rb
index 8612b5d710..9a54f6bfcc 100644
--- a/test/-ext-/string/test_fstring.rb
+++ b/test/-ext-/string/test_fstring.rb
@@ -71,4 +71,13 @@ class Test_String_Fstring < Test::Unit::TestCase
     str.freeze
     assert_fstring(str) {|s| assert_instance_of(S, s)}
   end
+
+  def test_shared_string_safety
+    -('a' * 30).force_encoding(Encoding::ASCII)
+    str = ('a' * 30).force_encoding(Encoding::ASCII).taint
+    frozen_str = Bug::String.rb_str_new_frozen(str)
+    assert_fstring(frozen_str) {|s| assert_equal(str, s)}
+    GC.start
+    assert_equal('a' * 30, str, "[Bug #16151]")
+  end
 end