diff --git a/src/Common/PlaceholderMethods.php b/src/Common/PlaceholderMethods.php
index 2ac69ed..c748035 100644
--- a/src/Common/PlaceholderMethods.php
+++ b/src/Common/PlaceholderMethods.php
@@ -33,7 +33,7 @@ public static function findInvalidPlaceholdersNames(array $placeholders, array $
         $invalidPlaceholderNames = array_intersect($placeholders, $contextKeys);
 
         $invalidPlaceholderNames = array_filter($invalidPlaceholderNames, function ($placeholder) {
-            return !PlaceholderMethods::isValidPlaceholderName($placeholder);
+            return !self::isValidPlaceholderName($placeholder);
         });
 
         return $invalidPlaceholderNames;
diff --git a/tests/PhpUnit/ExceptionsInContextConstraintTest.php b/tests/PhpUnit/ExceptionsInContextConstraintTest.php
index b41318c..b7025dd 100644
--- a/tests/PhpUnit/ExceptionsInContextConstraintTest.php
+++ b/tests/PhpUnit/ExceptionsInContextConstraintTest.php
@@ -23,7 +23,7 @@ protected function setUp()
 
     public function testConstraintDefinition()
     {
-        self::assertEquals(1, count($this->constraint));
+        self::assertCount(1, $this->constraint);
         self::assertEquals(
             'exceptions are located in the "exception" key',
             $this->constraint->toString()
diff --git a/tests/PhpUnit/LevelConstraintTest.php b/tests/PhpUnit/LevelConstraintTest.php
index b6a0d8a..4b6d1ca 100644
--- a/tests/PhpUnit/LevelConstraintTest.php
+++ b/tests/PhpUnit/LevelConstraintTest.php
@@ -24,7 +24,7 @@ protected function setUp()
 
     public function testConstraintDefinition()
     {
-        self::assertEquals(1, count($this->constraint));
+        self::assertCount(1, $this->constraint);
         self::assertEquals(
             'is a recognized log level (emergency, alert, critical, error, warning, notice, info, debug)',
             $this->constraint->toString()
diff --git a/tests/PhpUnit/MessageTypeConstraintTest.php b/tests/PhpUnit/MessageTypeConstraintTest.php
index a35b8a4..5b77d0c 100644
--- a/tests/PhpUnit/MessageTypeConstraintTest.php
+++ b/tests/PhpUnit/MessageTypeConstraintTest.php
@@ -25,7 +25,7 @@ protected function setUp()
 
     public function testConstraintDefinition()
     {
-        self::assertEquals(1, count($this->constraint));
+        self::assertCount(1, $this->constraint);
         self::assertEquals(
             'is string or a object with a __toString() method',
             $this->constraint->toString()
diff --git a/tests/PhpUnit/MissingPlaceholderInContextConstraintTest.php b/tests/PhpUnit/MissingPlaceholderInContextConstraintTest.php
index 30938a4..60325ae 100644
--- a/tests/PhpUnit/MissingPlaceholderInContextConstraintTest.php
+++ b/tests/PhpUnit/MissingPlaceholderInContextConstraintTest.php
@@ -31,7 +31,7 @@ protected function setUp()
 
     public function testConstraintDefinition()
     {
-        self::assertEquals(1, count($this->constraint));
+        self::assertCount(1, $this->constraint);
         self::assertEquals(
             'placeholder exists in the context array',
             $this->constraint->toString()
diff --git a/tests/PhpUnit/ValidPlaceholderNameInContextConstraintTest.php b/tests/PhpUnit/ValidPlaceholderNameInContextConstraintTest.php
index eeb05ed..ed299fb 100644
--- a/tests/PhpUnit/ValidPlaceholderNameInContextConstraintTest.php
+++ b/tests/PhpUnit/ValidPlaceholderNameInContextConstraintTest.php
@@ -27,7 +27,7 @@ protected function setUp()
 
     public function testConstraintDefinition()
     {
-        self::assertEquals(1, count($this->constraint));
+        self::assertCount(1, $this->constraint);
         self::assertEquals(
             'placeholder has valid name',
             $this->constraint->toString()