diff --git a/src/Forms/Helpers.php b/src/Forms/Helpers.php
index 55d701076..6d4702b67 100644
--- a/src/Forms/Helpers.php
+++ b/src/Forms/Helpers.php
@@ -102,6 +102,9 @@ public static function exportRules(Rules $rules): array
 				}
 				$op = Nette\Utils\Callback::toString($op);
 			}
+			if (is_callable($rule->message)) {
+				continue;
+			}
 			if ($rule->branch) {
 				$item = [
 					'op' => ($rule->isNegative ? '~' : '') . $op,
diff --git a/src/Forms/Rules.php b/src/Forms/Rules.php
index 6c2c8c9da..6c1b40311 100644
--- a/src/Forms/Rules.php
+++ b/src/Forms/Rules.php
@@ -69,7 +69,7 @@ public function isRequired(): bool
 	/**
 	 * Adds a validation rule for the current control.
 	 * @param  callable|string  $validator
-	 * @param  string|object  $errorMessage
+	 * @param  string|callable|object  $errorMessage
 	 * @return static
 	 */
 	public function addRule($validator, $errorMessage = null, $arg = null)
diff --git a/src/Forms/Validator.php b/src/Forms/Validator.php
index cb618a4fe..6ae8a7e88 100644
--- a/src/Forms/Validator.php
+++ b/src/Forms/Validator.php
@@ -51,6 +51,15 @@ class Validator
 	public static function formatMessage(Rule $rule, bool $withValue = true)
 	{
 		$message = $rule->message;
+		if (is_callable($message)) {
+			$params = Nette\Utils\Callback::toReflection($message)->getParameters();
+			if (isset($params[1])) {
+				$message = $message($rule->control, $rule->arg);
+			} else {
+				$message = $message($rule->control);
+			}
+		}
+
 		if ($message instanceof Nette\Utils\IHtmlString) {
 			return $message;
 
diff --git a/tests/Forms/Helpers.exportRules.phpt b/tests/Forms/Helpers.exportRules.phpt
index 5fc76976d..670ae121a 100644
--- a/tests/Forms/Helpers.exportRules.phpt
+++ b/tests/Forms/Helpers.exportRules.phpt
@@ -6,6 +6,7 @@
 
 declare(strict_types=1);
 
+use Nette\Forms\Controls\TextInput;
 use Nette\Forms\Form;
 use Nette\Forms\Helpers;
 use Tester\Assert;
@@ -91,3 +92,13 @@ test(function () {
 		],
 	], Helpers::exportRules($input2->getRules()));
 });
+
+
+test(function () {
+	$form = new Form;
+	$input = $form->addText('text');
+	$input->addRule(Form::EMAIL, function (TextInput $input, $arg) {
+		return $input->getValue() . ' is not valid e-mail address.';
+	});
+	Assert::same([], Helpers::exportRules($input->getRules()));
+});
diff --git a/tests/Forms/Rules.formatMessage.phpt b/tests/Forms/Rules.formatMessage.phpt
index 942d19202..c40fbed59 100644
--- a/tests/Forms/Rules.formatMessage.phpt
+++ b/tests/Forms/Rules.formatMessage.phpt
@@ -6,6 +6,7 @@
 
 declare(strict_types=1);
 
+use Nette\Forms\Controls\TextInput;
 use Nette\Forms\Form;
 use Tester\Assert;
 
@@ -34,11 +35,36 @@ $form->addText('special', 'Label:')
 	->addRule(Form::EMAIL, '%label %value is invalid [field %name] %d', $form['special'])
 	->setDefaultValue('xyz');
 
+$form->addText('function', 'Label:')
+	->setRequired()
+	->addRule(function (TextInput $input, string $arg) {
+		return strpos($input->getValue(), $arg) === false;
+	}, function (TextInput $input, string $arg) {
+		return "String “{$input->getValue()}” contains a letter “{$arg}”, which is not allowed";
+	}, 'a')
+	->setDefaultValue('banana');
+
+$form->addText('functionWithoutArg', 'Label:')
+	->setRequired()
+	->addRule(function (TextInput $input) {
+		return strpos($input->getValue(), 'e') === false;
+	}, function (TextInput $input) {
+		return "String “{$input->getValue()}” contains a letter “e”, which is not allowed";
+	})
+	->setDefaultValue('orange');
+
 $form->validate();
 
 Assert::true($form->hasErrors());
 
-Assert::same(['1 5', '5 1', '1 ', 'Label xyz is invalid [field special] xyz'], $form->getErrors());
+Assert::same([
+	'1 5',
+	'5 1',
+	'1 ',
+	'Label xyz is invalid [field special] xyz',
+	'String “banana” contains a letter “a”, which is not allowed',
+	'String “orange” contains a letter “e”, which is not allowed',
+], $form->getErrors());
 
 Assert::same([], $form->getOwnErrors());