diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec9b7446..5488ad17 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ Breaking changes:
 - [#1662](https://github.com/rails-api/active_model_serializers/pull/1662) Drop support for Rails 4.0 and Ruby 2.0.0. (@remear)
 
 Features:
+- [#1697](https://github.com/rails-api/active_model_serializers/pull/1697) Include actual exception message with custom exceptions;
+  `Test::Schema` exceptions are now `Minitest::Assertion`s. (@bf4)
 - [#1699](https://github.com/rails-api/active_model_serializers/pull/1699) String/Lambda support for conditional attributes/associations (@mtsmfm)
 - [#1687](https://github.com/rails-api/active_model_serializers/pull/1687) Only calculate `_cache_digest` (in `cache_key`) when `skip_digest` is false. (@bf4)
 - [#1647](https://github.com/rails-api/active_model_serializers/pull/1647) Restrict usage of `serializable_hash` options
diff --git a/lib/active_model_serializers/test/schema.rb b/lib/active_model_serializers/test/schema.rb
index 7674f6be..b356608e 100644
--- a/lib/active_model_serializers/test/schema.rb
+++ b/lib/active_model_serializers/test/schema.rb
@@ -14,8 +14,8 @@ module ActiveModelSerializers
         assert(matcher.call, matcher.message)
       end
 
-      MissingSchema = Class.new(Errno::ENOENT)
-      InvalidSchemaError = Class.new(StandardError)
+      MissingSchema = Class.new(Minitest::Assertion)
+      InvalidSchemaError = Class.new(Minitest::Assertion)
 
       class AssertResponseSchema
         attr_reader :schema_path, :response, :message
@@ -32,7 +32,7 @@ module ActiveModelSerializers
         def call
           json_schema.expand_references!(store: document_store)
           status, errors = json_schema.validate(response_body)
-          @message ||= errors.map(&:to_s).to_sentence
+          @message = [message, errors.map(&:to_s).to_sentence].compact.join(': ')
           status
         end
 
diff --git a/test/active_model_serializers/test/schema_test.rb b/test/active_model_serializers/test/schema_test.rb
index 16128437..105ac575 100644
--- a/test/active_model_serializers/test/schema_test.rb
+++ b/test/active_model_serializers/test/schema_test.rb
@@ -54,13 +54,15 @@ module ActiveModelSerializers
 
       def test_that_raises_error_with_a_custom_message_with_a_invalid_schema
         message = 'oh boy the show is broken'
+        exception_message = "#/name: failed schema #/properties/name: For 'properties/name', \"Name 1\" is not an integer. and #/description: failed schema #/properties/description: For 'properties/description', \"Description 1\" is not a boolean."
+        expected_message = "#{message}: #{exception_message}"
 
         get :show
 
         error = assert_raises Minitest::Assertion do
           assert_response_schema(nil, message)
         end
-        assert_equal(message, error.message)
+        assert_equal(expected_message, error.message)
       end
 
       def test_that_assert_with_a_custom_schema
@@ -102,14 +104,14 @@ module ActiveModelSerializers
       end
 
       def test_with_a_non_existent_file
-        message = %r{.* - No Schema file at test/support/schemas/non-existent.json}
+        message = 'No Schema file at test/support/schemas/non-existent.json'
 
         get :show
 
         error = assert_raises ActiveModelSerializers::Test::Schema::MissingSchema do
           assert_response_schema('non-existent.json')
         end
-        assert_match(message, error.message)
+        assert_equal(message, error.message)
       end
 
       def test_that_raises_with_a_invalid_json_body