diff --git a/tests/Monolog/Formatter/LogstashFormatterTest.php b/tests/Monolog/Formatter/LogstashFormatterTest.php
index b242d680..07a7efe2 100644
--- a/tests/Monolog/Formatter/LogstashFormatterTest.php
+++ b/tests/Monolog/Formatter/LogstashFormatterTest.php
@@ -176,6 +176,6 @@ class LogstashFormatterTest extends TestCase
         $this->assertEquals('ERROR', $message['level']);
         $this->assertEquals('test', $message['type']);
         $this->assertEquals('hostname', $message['host']);
-        $this->assertEquals('ÖWN; FBCR/OrangeEspaña; Versão/4.0; Färist', $message['extra']['user_agent']);
+        $this->assertEquals('�WN; FBCR/OrangeEspa�a; Vers�o/4.0; F�rist', $message['extra']['user_agent']);
     }
 }
diff --git a/tests/Monolog/Formatter/NormalizerFormatterTest.php b/tests/Monolog/Formatter/NormalizerFormatterTest.php
index d3661c5a..9ea7f080 100644
--- a/tests/Monolog/Formatter/NormalizerFormatterTest.php
+++ b/tests/Monolog/Formatter/NormalizerFormatterTest.php
@@ -270,7 +270,7 @@ class NormalizerFormatterTest extends TestCase
         $this->assertEquals('Over 1000 items (2000 total), aborting normalization', $res['context'][0]['...']);
     }
 
-    public function testThrowsOnInvalidEncoding()
+    public function testIgnoresInvalidEncoding()
     {
         $formatter = new NormalizerFormatter();
         $reflMethod = new \ReflectionMethod($formatter, 'toJson');
@@ -280,9 +280,7 @@ class NormalizerFormatterTest extends TestCase
         $record = new \stdClass;
         $record->message = "\xB1\x31";
 
-        $this->expectException(\RuntimeException::class);
-
-        $reflMethod->invoke($formatter, $record);
+        $this->assertsame('{"message":"�1"}', $reflMethod->invoke($formatter, $record));
     }
 
     public function testConvertsInvalidEncodingAsLatin9()
@@ -293,7 +291,7 @@ class NormalizerFormatterTest extends TestCase
 
         $res = $reflMethod->invoke($formatter, ['message' => "\xA4\xA6\xA8\xB4\xB8\xBC\xBD\xBE"]);
 
-        $this->assertSame('{"message":"€ŠšŽžŒœŸ"}', $res);
+        $this->assertSame('{"message":"��������"}', $res);
     }
 
     public function testMaxNormalizeDepth()
diff --git a/tests/Monolog/Handler/RotatingFileHandlerTest.php b/tests/Monolog/Handler/RotatingFileHandlerTest.php
index 75bcab30..5446f40e 100644
--- a/tests/Monolog/Handler/RotatingFileHandlerTest.php
+++ b/tests/Monolog/Handler/RotatingFileHandlerTest.php
@@ -137,7 +137,7 @@ class RotatingFileHandlerTest extends TestCase
         $handler = new RotatingFileHandler(__DIR__.'/Fixtures/foo.rot', 2);
         if (!$valid) {
             $this->expectException(InvalidArgumentException::class);
-            $this->expectExceptionMessageRegExp('~^Invalid date format~');
+            $this->expectExceptionMessageMatches('~^Invalid date format~');
         }
         $handler->setFilenameFormat('{filename}-{date}', $dateFormat);
         $this->assertTrue(true);
@@ -178,7 +178,7 @@ class RotatingFileHandlerTest extends TestCase
         $handler = new RotatingFileHandler(__DIR__.'/Fixtures/foo.rot', 2);
         if (!$valid) {
             $this->expectException(InvalidArgumentException::class);
-            $this->expectExceptionMessageRegExp('~^Invalid filename format~');
+            $this->expectExceptionMessageMatches('~^Invalid filename format~');
         }
 
         $handler->setFilenameFormat($filenameFormat, RotatingFileHandler::FILE_PER_DAY);