diff --git a/test/poison/encoder_test.exs b/test/poison/encoder_test.exs
index 4c324a0..bc251bf 100644
--- a/test/poison/encoder_test.exs
+++ b/test/poison/encoder_test.exs
@@ -69,7 +69,7 @@ defmodule Poison.EncoderTest do
       assert to_json(value) == ~s("#{value}")
     end
 
-    check all str <- string(Enum.concat(0xA0..0xD800, 0xE000..0x10000)),
+    check all str <- string(Enum.concat(0xA0..0xD7FF, 0xE000..0x10000)),
               str != "",
               elem <- member_of(String.codepoints(str)),
               <<codepoint::utf8>> = elem do
diff --git a/test/poison/parser_test.exs b/test/poison/parser_test.exs
index dee2c9a..11fb174 100644
--- a/test/poison/parser_test.exs
+++ b/test/poison/parser_test.exs
@@ -134,7 +134,7 @@ defmodule Poison.ParserTest do
       assert parse!(~s("#{str}")) == str
     end
 
-    check all value <- integer(0x0..0xD800) do
+    check all value <- integer(0x0..0xD7FF) do
       seq = value |> Integer.to_string(16) |> String.pad_leading(4, "0")
       assert parse!(~s("\\u#{seq}")) == <<value::utf8>>
     end