diff --git a/src/Convert/Strings.php b/src/Convert/Strings.php
index dd30b47..e4e40f5 100644
--- a/src/Convert/Strings.php
+++ b/src/Convert/Strings.php
@@ -287,6 +287,10 @@ class Strings
 		// Remove all spaces
 		$input = str_replace(' ', '', $input);
 		$result = [];
+		// if there is no - inside, return unique characters as array
+		if (strpos($input, '-') === false) {
+			return array_unique(mb_str_split($input));
+		}
 		// Find all patterns like "A-Z" (character-dash-character)
 		preg_match_all('/(.)-(.)/u', $input, $matches, PREG_SET_ORDER);
 		foreach ($matches as $match) {
diff --git a/test/phpunit/Convert/CoreLibsConvertStringsTest.php b/test/phpunit/Convert/CoreLibsConvertStringsTest.php
index 26c635e..017c4ec 100644
--- a/test/phpunit/Convert/CoreLibsConvertStringsTest.php
+++ b/test/phpunit/Convert/CoreLibsConvertStringsTest.php
@@ -743,6 +743,11 @@ final class CoreLibsConvertStringsTest extends TestCase
 				'abcdefghijklmnopqrstuvwxyz0123',
 				null,
 			],
+			'range without dashes' => [
+				['abcddfff'],
+				'abcdf',
+				null,
+			],
 			'invalid ranges' => [
 				['a-あ', 'A-あ', '0-あ'],
 				'',