diff --git a/lib/nimble_options.ex b/lib/nimble_options.ex
index 397b6c1..f3ecf7e 100644
--- a/lib/nimble_options.ex
+++ b/lib/nimble_options.ex
@@ -601,8 +601,8 @@ defmodule NimbleOptions do
     end
   end
 
-  defp validate_type(:integer, key, value, redact) when not is_integer(value) do
-    structured_error_tuple(key, value, "integer", redact)
+  defp validate_type(:integer = type, key, value, redact) when not is_integer(value) do
+    structured_error_tuple(key, value, {:type, type}, "integer", redact)
   end
 
   defp validate_type(:non_neg_integer, key, value, redact)
@@ -1019,11 +1019,16 @@ defmodule NimbleOptions do
     {:error, %ValidationError{key: key, message: message, redact: redact, value: value}}
   end
 
+  # FIX: remove after error types are implemented
   defp structured_error_tuple(key, value, expected, redact?) do
-    structured_error_tuple(key, value, expected, inspect(value), redact?)
+    structured_error_tuple(key, value, false, expected, redact?)
   end
 
-  defp structured_error_tuple(key, value, expected, got, redact?) do
+  defp structured_error_tuple(key, value, type, expected, redact?) do
+    structured_error_tuple(key, value, type, expected, inspect(value), redact?)
+  end
+
+  defp structured_error_tuple(key, value, validation, expected, got, redact?) do
     message =
       if redact? do
         "invalid value for #{render_key(key)}: expected #{expected}"
@@ -1031,7 +1036,14 @@ defmodule NimbleOptions do
         "invalid value for #{render_key(key)}: expected #{expected}, got: #{got}"
       end
 
-    {:error, %ValidationError{key: key, message: message, redact: redact?, value: value}}
+    {:error,
+     %ValidationError{
+       key: key,
+       message: message,
+       redact: redact?,
+       value: value,
+       validation: validation
+     }}
   end
 
   defp render_key({__MODULE__, :key}), do: "map key"
diff --git a/lib/nimble_options/validation_error.ex b/lib/nimble_options/validation_error.ex
index 0115cfe..ab391e7 100644
--- a/lib/nimble_options/validation_error.ex
+++ b/lib/nimble_options/validation_error.ex
@@ -12,6 +12,7 @@ defmodule NimbleOptions.ValidationError do
           key: atom(),
           keys_path: [atom()],
           redact: boolean,
+          validation: :required | {:type, term()},
           value: term()
         }
 
@@ -28,8 +29,10 @@ defmodule NimbleOptions.ValidationError do
     * `:value` (`t:term/0`) - The value that failed to validate. This field is `nil` if there
       was no value provided.
 
+    * `:validation` (`:required` or `{:type, type}`) - The validation that failed.
+
   """
-  defexception [:message, :key, :value, keys_path: [], redact: false]
+  defexception [:message, :key, :validation, :value, keys_path: [], redact: false]
 
   @impl true
   def message(%__MODULE__{message: message, keys_path: keys_path}) do
diff --git a/test/nimble_options_test.exs b/test/nimble_options_test.exs
index 3992c75..d74ab8b 100644
--- a/test/nimble_options_test.exs
+++ b/test/nimble_options_test.exs
@@ -292,6 +292,7 @@ defmodule NimbleOptionsTest do
                 %ValidationError{
                   key: :min_demand,
                   value: 1.5,
+                  validation: {:type, :integer},
                   message: "invalid value for :min_demand option: expected integer, got: 1.5"
                 }}
 
@@ -300,6 +301,7 @@ defmodule NimbleOptionsTest do
                 %ValidationError{
                   key: :min_demand,
                   value: :an_atom,
+                  validation: {:type, :integer},
                   message: "invalid value for :min_demand option: expected integer, got: :an_atom"
                 }}
     end
@@ -312,6 +314,7 @@ defmodule NimbleOptionsTest do
                 %ValidationError{
                   key: :min_demand,
                   value: 1.5,
+                  validation: {:type, :integer},
                   message: "invalid value for :min_demand option: expected integer",
                   redact: true
                 }}
@@ -2250,7 +2253,7 @@ defmodule NimbleOptionsTest do
   end
 
   # No other test is passing in `opts` as a map, so these are just some white box tests for sanity checking
-  describe "can use a map for validate/2" do
+  test "can use a map for validate/2" do
     schema = []
     opts = %{}
     assert NimbleOptions.validate(opts, schema) == {:ok, %{}}