diff --git a/lib/ecto/type.ex b/lib/ecto/type.ex
index 243d94dad8..a5b0627fa3 100644
--- a/lib/ecto/type.ex
+++ b/lib/ecto/type.ex
@@ -1179,9 +1179,9 @@ defmodule Ecto.Type do
            minute::2-bytes>>
        )
        when sep in [?\s, ?T] do
-    case NaiveDateTime.new(to_i(year), to_i(month), to_i(day), to_i(hour), to_i(minute), 0) do
-      {:ok, _} = ok -> ok
-      _ -> :error
+    with {:ok, date} <- cast_date(to_i(year), to_i(month), to_i(day)),
+         {:ok, time} <- cast_time(to_i(hour), to_i(minute), 0, nil) do
+      NaiveDateTime.new(date, time)
     end
   end
 
@@ -1232,9 +1232,9 @@ defmodule Ecto.Type do
            minute::2-bytes>>
        )
        when sep in [?\s, ?T] do
-    case NaiveDateTime.new(to_i(year), to_i(month), to_i(day), to_i(hour), to_i(minute), 0) do
-      {:ok, naive_datetime} -> {:ok, DateTime.from_naive!(naive_datetime, "Etc/UTC")}
-      _ -> :error
+    with {:ok, date} <- cast_date(to_i(year), to_i(month), to_i(day)),
+         {:ok, time} <- cast_time(to_i(hour), to_i(minute), 0, nil) do
+      DateTime.new(date, time, "Etc/UTC")
     end
   end
 
diff --git a/test/ecto/type_test.exs b/test/ecto/type_test.exs
index 7174a20e2f..06743295ad 100644
--- a/test/ecto/type_test.exs
+++ b/test/ecto/type_test.exs
@@ -657,6 +657,9 @@ defmodule Ecto.TypeTest do
       assert Ecto.Type.cast(:naive_datetime, "2015-01-23P23:50:07") == :error
       assert Ecto.Type.cast(:naive_datetime, "2015-01-23 23:50.123") == :error
       assert Ecto.Type.cast(:naive_datetime, "2015-01-23 23:50Z") == :error
+      assert Ecto.Type.cast(:naive_datetime, "abcd-01-23 23:50") == :error
+      assert Ecto.Type.cast(:naive_datetime, "2015-01-23 ab:50") == :error
+      assert Ecto.Type.cast(:naive_datetime, "2015-01-23T23:5x") == :error
 
       assert Ecto.Type.cast(:naive_datetime, %{
                "year" => "2015",
@@ -1013,6 +1016,9 @@ defmodule Ecto.TypeTest do
       assert Ecto.Type.cast(:utc_datetime, "2015-01-23P23:50:07") == :error
       assert Ecto.Type.cast(:utc_datetime, "2015-01-23 23:50.123") == :error
       assert Ecto.Type.cast(:utc_datetime, "2015-01-23 23:50Z") == :error
+      assert Ecto.Type.cast(:utc_datetime, "abcd-01-23 23:50") == :error
+      assert Ecto.Type.cast(:utc_datetime, "2015-01-23 ab:50") == :error
+      assert Ecto.Type.cast(:utc_datetime, "2015-01-23T23:5x") == :error
 
       assert Ecto.Type.cast(:utc_datetime, %{
                "year" => "2015",