diff --git a/README.md b/README.md
index fd616ca..b9a3fb7 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ Add the project to your Mix dependencies in `mix.exs`:
 ```elixir
 defp deps do
   [
-    {:ex_json_schema, "~> 0.9.0"}
+    {:ex_json_schema, "~> 0.9.1"}
   ]
 end
 ```
diff --git a/lib/ex_json_schema/validator/format.ex b/lib/ex_json_schema/validator/format.ex
index 1f94097..204e1fb 100644
--- a/lib/ex_json_schema/validator/format.ex
+++ b/lib/ex_json_schema/validator/format.ex
@@ -64,9 +64,9 @@ defmodule ExJsonSchema.Validator.Format do
   defp do_validate(_, "date-time" = format, data) do
     data
     |> String.upcase()
-    |> DateTime.from_iso8601()
+    |> NaiveDateTime.from_iso8601()
     |> case do
-      {:ok, %DateTime{}, _} -> []
+      {:ok, %NaiveDateTime{}} -> []
       _ -> [%Error{error: %Error.Format{expected: format}}]
     end
   end
diff --git a/mix.exs b/mix.exs
index 96e238c..5d571c1 100644
--- a/mix.exs
+++ b/mix.exs
@@ -2,7 +2,7 @@ defmodule ExJsonSchema.Mixfile do
   use Mix.Project
 
   @source_url "https://github.com/jonasschmidt/ex_json_schema"
-  @version "0.9.0"
+  @version "0.9.1"
 
   def project do
     [
diff --git a/test/ex_json_schema/validator_test.exs b/test/ex_json_schema/validator_test.exs
index a190edc..7d22d04 100644
--- a/test/ex_json_schema/validator_test.exs
+++ b/test/ex_json_schema/validator_test.exs
@@ -667,10 +667,14 @@ defmodule ExJsonSchema.ValidatorTest do
     assert :ok == validate(%{"format" => "date-time"}, false)
   end
 
+  test "format validation succeeds for datetime without tz offset" do
+    assert :ok == validate(%{"format" => "date-time"}, "2012-12-12 12:12:12")
+  end
+
   test "validation errors for date-time format" do
     assert_validation_errors(
       %{"format" => "date-time"},
-      "2012-12-12 12:12:12",
+      "2012-12-12 12:12:12-1.5",
       [{"Expected to be a valid ISO 8601 date-time.", "#"}],
       [%Error{error: %Error.Format{expected: "date-time"}, path: "#"}]
     )