diff --git a/app/Util/Lexer/Regex.php b/app/Util/Lexer/Regex.php
index c24e0d4b0..ecc468d05 100755
--- a/app/Util/Lexer/Regex.php
+++ b/app/Util/Lexer/Regex.php
@@ -162,9 +162,9 @@ abstract class Regex
         //      look-ahead capture here and don't append $after when we return.
         $tmp['valid_mention_preceding_chars'] = '([^a-zA-Z0-9_!#\$%&*@＠\/]|^|(?:^|[^a-z0-9_+~.-])RT:?)';
 
-        $re['valid_mentions_or_lists'] = '/'.$tmp['valid_mention_preceding_chars'].'(['.$tmp['at_signs'].'])([a-z0-9_]{1,20})((\/[a-z][a-z0-9_\-]{0,24})?(?=(.*|$))(?:@[a-z0-9\.\-]+[a-z0-9]+)?)/i';
+        $re['valid_mentions_or_lists'] = '/'.$tmp['valid_mention_preceding_chars'].'(['.$tmp['at_signs'].'])([a-z0-9_\-.]{1,20})((\/[a-z][a-z0-9_\-]{0,24})?(?=(.*|$))(?:@[a-z0-9\.\-]+[a-z0-9]+)?)/i';
 
-        $re['valid_reply'] = '/^(?:['.$tmp['spaces'].'])*['.$tmp['at_signs'].']([a-z0-9_]{1,20})(?=(.*|$))/iu';
+        $re['valid_reply'] = '/^(?:['.$tmp['spaces'].'])*['.$tmp['at_signs'].']([a-z0-9_\-.]{1,20})(?=(.*|$))/iu';
         $re['end_mention_match'] = '/\A(?:['.$tmp['at_signs'].']|['.$tmp['latin_accents'].']|:\/\/)/iu';
 
         // URL related hash regex collection
diff --git a/tests/Unit/Lexer/UsernameTest.php b/tests/Unit/Lexer/UsernameTest.php
new file mode 100644
index 000000000..e5c310db7
--- /dev/null
+++ b/tests/Unit/Lexer/UsernameTest.php
@@ -0,0 +1,179 @@
+<?php
+
+namespace Tests\Unit\Lexer;
+
+use Tests\TestCase;
+use Illuminate\Foundation\Testing\WithFaker;
+use App\Util\Lexer\Autolink;
+use App\Util\Lexer\Extractor;
+
+class UsernameTest extends TestCase
+{
+	/** @test **/
+	public function genericUsername()
+	{
+		$username = '@dansup';
+		$entities = Extractor::create()->extract($username);
+		$autolink = Autolink::create()->autolink($username);
+		$expectedAutolink = '<a class="u-url mention" href="https://pixelfed.dev/dansup" rel="external nofollow noopener" target="_blank">@dansup</a>';
+		$expectedEntity = [
+			"hashtags" => [],
+			"urls" => [],
+			"mentions" => [
+				"dansup",
+			],
+			"replyto" => "dansup",
+			"hashtags_with_indices" => [],
+			"urls_with_indices" => [],
+			"mentions_with_indices" => [
+				[
+					"screen_name" => "dansup",
+					"indices" => [
+						0,
+						7,
+					],
+				],
+			],
+		];
+		$this->assertEquals($expectedAutolink, $autolink);
+		$this->assertEquals($expectedEntity, $entities);
+	}
+
+	/** @test **/
+	public function usernameWithPeriod()
+	{
+		$username = '@dansup.two';
+		$autolink = Autolink::create()->autolink($username);
+		$entities = Extractor::create()->extract($username);
+		$expectedAutolink = '<a class="u-url mention" href="https://pixelfed.dev/dansup.two" rel="external nofollow noopener" target="_blank">@dansup.two</a>';
+		$expectedEntity = [
+			"hashtags" => [],
+			"urls" => [],
+			"mentions" => [
+				"dansup.two",
+			],
+			"replyto" => "dansup.two",
+			"hashtags_with_indices" => [],
+			"urls_with_indices" => [],
+			"mentions_with_indices" => [
+				[
+					"screen_name" => "dansup.two",
+					"indices" => [
+						0,
+						11,
+					],
+				],
+			],
+		];
+		$this->assertEquals($expectedAutolink, $autolink);
+		$this->assertEquals($expectedEntity, $entities);
+	}
+
+	/** @test **/
+	public function usernameWithDash()
+	{
+		$username = '@dansup-too';
+		$autolink = Autolink::create()->autolink($username);
+		$entities = Extractor::create()->extract($username);
+		$expectedAutolink = '<a class="u-url mention" href="https://pixelfed.dev/dansup-too" rel="external nofollow noopener" target="_blank">@dansup-too</a>';
+		$expectedEntity = [
+			"hashtags" => [],
+			"urls" => [],
+			"mentions" => [
+				"dansup-too",
+			],
+			"replyto" => "dansup-too",
+			"hashtags_with_indices" => [],
+			"urls_with_indices" => [],
+			"mentions_with_indices" => [
+				[
+					"screen_name" => "dansup-too",
+					"indices" => [
+						0,
+						11,
+					],
+				],
+			],
+		];
+		$this->assertEquals($expectedAutolink, $autolink);
+		$this->assertEquals($expectedEntity, $entities);
+	}
+
+	/** @test **/
+	public function usernameWithUnderscore()
+	{
+		$username = '@dansup_too';
+		$autolink = Autolink::create()->autolink($username);
+		$entities = Extractor::create()->extract($username);
+		$expectedAutolink = '<a class="u-url mention" href="https://pixelfed.dev/dansup_too" rel="external nofollow noopener" target="_blank">@dansup_too</a>';
+		$expectedEntity = [
+			"hashtags" => [],
+			"urls" => [],
+			"mentions" => [
+				"dansup_too",
+			],
+			"replyto" => "dansup_too",
+			"hashtags_with_indices" => [],
+			"urls_with_indices" => [],
+			"mentions_with_indices" => [
+				[
+					"screen_name" => "dansup_too",
+					"indices" => [
+						0,
+						11,
+					],
+				],
+			],
+		];
+		$this->assertEquals($expectedAutolink, $autolink);
+		$this->assertEquals($expectedEntity, $entities);
+	}
+
+	/** @test **/
+	public function multipleMentions()
+	{
+		$text = 'hello @dansup and @pixelfed.team from @username_underscore';
+		$autolink = Autolink::create()->autolink($text);
+		$entities = Extractor::create()->extract($text);
+		$expectedAutolink = 'hello <a class="u-url mention" href="https://pixelfed.dev/dansup" rel="external nofollow noopener" target="_blank">@dansup</a> and <a class="u-url mention" href="https://pixelfed.dev/pixelfed.team" rel="external nofollow noopener" target="_blank">@pixelfed.team</a> from <a class="u-url mention" href="https://pixelfed.dev/username_underscore" rel="external nofollow noopener" target="_blank">@username_underscore</a>';
+		$expectedEntity = [
+			"hashtags" => [],
+			"urls" => [],
+			"mentions" => [
+				"dansup",
+				"pixelfed.team",
+				"username_underscore",
+			],
+			"replyto" => null,
+			"hashtags_with_indices" => [],
+			"urls_with_indices" => [],
+			"mentions_with_indices" => [
+				[
+					"screen_name" => "dansup",
+					"indices" => [
+						6,
+						13,
+					],
+				],
+				[
+					"screen_name" => "pixelfed.team",
+					"indices" => [
+						18,
+						32,
+					],
+				],
+				[
+					"screen_name" => "username_underscore",
+					"indices" => [
+						38,
+						58,
+					],
+				],
+			],
+		];
+
+		$this->assertEquals($expectedAutolink, $autolink);
+		$this->assertEquals($expectedEntity, $entities);
+	}
+
+}
\ No newline at end of file