diff --git a/src/Dibi/Translator.php b/src/Dibi/Translator.php
index c1e07025..6fab1315 100644
--- a/src/Dibi/Translator.php
+++ b/src/Dibi/Translator.php
@@ -350,11 +350,15 @@ final class Translator
 				case 'u':  // unsigned int, ignored
 					if ($value === null) {
 						return 'NULL';
-					} elseif (is_string($value) && preg_match('#[+-]?\d++(?:e\d+)?\z#A', $value)) {
-						return $value; // support for long numbers - keep them unchanged
-					} elseif (is_string($value) && substr($value, 1, 1) === 'x' && is_numeric($value)) {
-						trigger_error('Support for hex strings has been deprecated.', E_USER_DEPRECATED);
-						return (string) hexdec($value);
+					} elseif (is_string($value)) {
+						if (preg_match('#[+-]?\d++(?:e\d+)?\z#A', $value)) {
+							return $value; // support for long numbers - keep them unchanged
+						} elseif (substr($value, 1, 1) === 'x' && is_numeric($value)) {
+							trigger_error('Support for hex strings has been deprecated.', E_USER_DEPRECATED);
+							return (string) hexdec($value);
+						} else {
+							throw new Exception("Expected number, '$value' given.");
+						}
 					} else {
 						return (string) (int) $value;
 					}
@@ -362,8 +366,12 @@ final class Translator
 				case 'f':  // float
 					if ($value === null) {
 						return 'NULL';
-					} elseif (is_string($value) && is_numeric($value) && substr($value, 1, 1) !== 'x') {
-						return $value; // support for extreme numbers - keep them unchanged
+					} elseif (is_string($value)) {
+						if (is_numeric($value) && substr($value, 1, 1) !== 'x') {
+							return $value; // support for long numbers - keep them unchanged
+						} else {
+							throw new Exception("Expected number, '$value' given.");
+						}
 					} else {
 						return rtrim(rtrim(number_format($value + 0, 10, '.', ''), '0'), '.');
 					}
diff --git a/tests/dibi/Translator.phpt b/tests/dibi/Translator.phpt
index fee46ad9..a2b8f093 100644
--- a/tests/dibi/Translator.phpt
+++ b/tests/dibi/Translator.phpt
@@ -497,11 +497,11 @@ Assert::same('INSERT INTO test **Multi-insert array "num%i" is different**', $e-
 $array6 = [
 	'id' => [1, 2, 3, 4],
 	'text' => ['ahoj', 'jak', 'se', ['SUM(%i)', '5']],
-	'num%i' => ['1', '', 10.3, 1],
+	'num%i' => ['1', '-1', 10.3, 1],
 ];
 
 Assert::same(
-	reformat('INSERT INTO test ([id], [text], [num]) VALUES (1, \'ahoj\', 1), (2, \'jak\', 0), (3, \'se\', 10), (4, SUM(5), 1)'),
+	reformat('INSERT INTO test ([id], [text], [num]) VALUES (1, \'ahoj\', 1), (2, \'jak\', -1), (3, \'se\', 10), (4, SUM(5), 1)'),
 	$conn->translate('INSERT INTO test %m', $array6)
 );
 
@@ -521,10 +521,13 @@ Assert::same(
 	$conn->translate('INSERT INTO [test.*]')
 );
 
-Assert::same(
-	reformat('INSERT INTO 0'),
-	@$conn->translate('INSERT INTO %f', 'ahoj') // triggers warning in PHP 7.1
-);
+Assert::exception(function () use ($conn) {
+	$conn->translate('INSERT INTO %i', 'ahoj');
+}, 'Dibi\Exception', "Expected number, 'ahoj' given.");
+
+Assert::exception(function () use ($conn) {
+	$conn->translate('INSERT INTO %f', 'ahoj');
+}, 'Dibi\Exception', "Expected number, 'ahoj' given.");
 
 
 Assert::same(