diff --git a/.travis.yml b/.travis.yml
index 6a3ea0e..abcda6e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,9 +13,8 @@ env:
     - DEPENDENCIES='beta'
 
 php:
-    - 7.0
-    - 7.1
     - 7.2
+    - 7.4
 
 install:
     - if [[ $DEPENDENCIES = 'beta' ]]; then composer config minimum-stability beta; fi
diff --git a/src/Context/ApiContext.php b/src/Context/ApiContext.php
index 8b01d04..6f99e30 100644
--- a/src/Context/ApiContext.php
+++ b/src/Context/ApiContext.php
@@ -364,7 +364,7 @@ public function validateCollectionIsEmpty(string $name)
      */
     public function printCollectionJsonSchema(string $name)
     {
-        echo json_encode($this->schemaGenerator->generate($this->helper->getReflectionClass($name), ['collection' => true, 'root' => true]), JSON_PRETTY_PRINT);
+        echo json_encode($this->schemaGenerator->generate($this->helper->getReflectionClass($name), ['collection' => true, 'root' => true]), \JSON_PRETTY_PRINT);
     }
 
     /**
@@ -372,7 +372,7 @@ public function printCollectionJsonSchema(string $name)
      */
     public function printItemJsonSchema(string $name)
     {
-        echo json_encode($this->schemaGenerator->generate($this->helper->getReflectionClass($name), ['collection' => false, 'root' => true]), JSON_PRETTY_PRINT);
+        echo json_encode($this->schemaGenerator->generate($this->helper->getReflectionClass($name), ['collection' => false, 'root' => true]), \JSON_PRETTY_PRINT);
     }
 
     /**
@@ -380,7 +380,7 @@ public function printItemJsonSchema(string $name)
      */
     public function printJsonData()
     {
-        echo json_encode($this->lastRequestJson, JSON_PRETTY_PRINT);
+        echo json_encode($this->lastRequestJson, \JSON_PRETTY_PRINT);
     }
 
     private function findObject(string $name, $value)
diff --git a/src/Populator/Populator.php b/src/Populator/Populator.php
index bf7e553..8216893 100644
--- a/src/Populator/Populator.php
+++ b/src/Populator/Populator.php
@@ -92,7 +92,7 @@ public function getObject(\ReflectionClass $reflectionClass, array $values = [])
         foreach (array_merge($classMetadata->getFieldNames(), $classMetadata->getAssociationNames()) as $property) {
             $mapping = $this->getMapping($classMetadata, $property);
             // Property is already filled, or is not required, or a primary key (except for association primary key)
-            if (array_key_exists($property, $values) || $mapping['nullable'] || ($classMetadata->isIdentifier($property) && $classMetadata->hasField($property))) {
+            if (\array_key_exists($property, $values) || $mapping['nullable'] || ($classMetadata->isIdentifier($property) && $classMetadata->hasField($property))) {
                 continue;
             }
             if ($reflectionClass->hasProperty($property)) {
@@ -147,7 +147,7 @@ public function getRequestData(\ReflectionClass $reflectionClass, string $operat
         /** @var ClassMetadataInfo $classMetadata */
         $classMetadata = $this->registry->getManagerForClass($className)->getClassMetadata($className);
         foreach ($this->propertyInfo->getProperties($className, $groups ? ['serializer_groups' => $groups] : []) as $property) {
-            if (!$reflectionClass->hasProperty($property) || !$this->isRequired($reflectionClass->getProperty($property), $validationGroups) || array_key_exists($property, $values) || ('put' === $operation && 0 < \count($originalValues))) {
+            if (!$reflectionClass->hasProperty($property) || !$this->isRequired($reflectionClass->getProperty($property), $validationGroups) || \array_key_exists($property, $values) || ('put' === $operation && 0 < \count($originalValues))) {
                 continue;
             }
             $values[$property] = $this->guesser->getValue($this->getMapping($classMetadata, $property));
@@ -182,7 +182,7 @@ public function getMapping(ClassMetadataInfo $classMetadata, string $property):
             $this->mapping[$className][$fieldName] = $classMetadata->getFieldMapping($fieldName);
         }
         foreach ($this->propertyInfo->getProperties($className) as $fieldName) {
-            if (array_key_exists($fieldName, $this->mapping[$className])) {
+            if (\array_key_exists($fieldName, $this->mapping[$className])) {
                 continue;
             }
 
@@ -246,6 +246,6 @@ private function filterOperations(array $operations, string $operation): array
     {
         return array_filter($operations, function ($value, $key) use ($operation) {
             return $operation === (\is_int($key) ? $value : $key);
-        }, ARRAY_FILTER_USE_BOTH);
+        }, \ARRAY_FILTER_USE_BOTH);
     }
 }
diff --git a/src/SchemaGenerator/ObjectSchemaGenerator.php b/src/SchemaGenerator/ObjectSchemaGenerator.php
index be30f88..875d787 100644
--- a/src/SchemaGenerator/ObjectSchemaGenerator.php
+++ b/src/SchemaGenerator/ObjectSchemaGenerator.php
@@ -94,7 +94,7 @@ public function generate(\ReflectionClass $reflectionClass, array $context = [])
             $context['depth'] = 0;
         }
         if ($context['depth'] > self::MAX_DEPTH) {
-            throw new MaxDepthException(sprintf('Maximum depth of %d has been reached. This could be caused by a circular reference due to serialization groups.%sPath: %s', self::MAX_DEPTH, PHP_EOL, implode('->', $this->path)));
+            throw new MaxDepthException(sprintf('Maximum depth of %d has been reached. This could be caused by a circular reference due to serialization groups.%sPath: %s', self::MAX_DEPTH, \PHP_EOL, implode('->', $this->path)));
         }
         ++$context['depth'];
         $className = $reflectionClass->name;
diff --git a/src/Transformer/EntityTransformer.php b/src/Transformer/EntityTransformer.php
index 60583d8..c5b2bf7 100644
--- a/src/Transformer/EntityTransformer.php
+++ b/src/Transformer/EntityTransformer.php
@@ -76,7 +76,7 @@ public function toObject(array $mapping, $value)
                     break;
                 case Type::GUID:
                     // Support for PostgreSQL native type
-                    if (!\preg_match('/^(\{{0,1}([0-9a-fA-F]){8}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){12}\}{0,1})$/', (string) $value)) {
+                    if (!preg_match('/^(\{{0,1}([0-9a-fA-F]){8}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){12}\}{0,1})$/', (string) $value)) {
                         $type = 'invalid';
                     }
                     break;
@@ -84,7 +84,7 @@ public function toObject(array $mapping, $value)
                 case Type::DATETIME:
                 case Type::DATETIMETZ:
                     // Support for PostgreSQL native type
-                    if (!\preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])/', (string) $value)) {
+                    if (!preg_match('/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])/', (string) $value)) {
                         $type = 'invalid';
                     }
                     break;