diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 817b034..e972afa 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -240,6 +240,10 @@
     <!-- Forbid using absolute class name references -->
     <rule ref="SlevomatCodingStandard.Namespaces.ReferenceUsedNamesOnly">
         <properties>
+            <property name="allowFallbackGlobalConstants" value="false"/>
+            <property name="allowFallbackGlobalFunctions" value="false"/>
+            <property name="allowFullyQualifiedGlobalConstants" value="false"/>
+            <property name="allowFullyQualifiedGlobalFunctions" value="false"/>
             <property name="allowFullyQualifiedExceptions" value="true"/>
             <property name="allowPartialUses" value="false"/>
             <property name="fullyQualifiedKeywords" type="array">
diff --git a/src/Codec/GuidStringCodec.php b/src/Codec/GuidStringCodec.php
index 40d8d71..bbc6d60 100644
--- a/src/Codec/GuidStringCodec.php
+++ b/src/Codec/GuidStringCodec.php
@@ -16,6 +16,9 @@ namespace Ramsey\Uuid\Codec;
 
 use Ramsey\Uuid\UuidInterface;
 
+use function bin2hex;
+use function substr;
+
 /**
  * GuidStringCodec encodes and decodes globally unique identifiers (GUID)
  *
diff --git a/src/Codec/OrderedTimeCodec.php b/src/Codec/OrderedTimeCodec.php
index 540dd57..61200e9 100644
--- a/src/Codec/OrderedTimeCodec.php
+++ b/src/Codec/OrderedTimeCodec.php
@@ -20,6 +20,9 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface as Rfc4122FieldsInterface;
 use Ramsey\Uuid\Uuid;
 use Ramsey\Uuid\UuidInterface;
 
+use function strlen;
+use function substr;
+
 /**
  * OrderedTimeCodec encodes and decodes a UUID, optimizing the byte order for
  * more efficient storage
diff --git a/src/Codec/StringCodec.php b/src/Codec/StringCodec.php
index 478daad..2dbf8f9 100644
--- a/src/Codec/StringCodec.php
+++ b/src/Codec/StringCodec.php
@@ -21,6 +21,12 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface;
 use Ramsey\Uuid\Uuid;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function implode;
+use function str_replace;
+use function strlen;
+use function substr;
+
 /**
  * StringCodec encodes and decodes RFC 4122 UUIDs
  *
diff --git a/src/Codec/TimestampFirstCombCodec.php b/src/Codec/TimestampFirstCombCodec.php
index 4ab58eb..3f53cb1 100644
--- a/src/Codec/TimestampFirstCombCodec.php
+++ b/src/Codec/TimestampFirstCombCodec.php
@@ -17,6 +17,11 @@ namespace Ramsey\Uuid\Codec;
 use Ramsey\Uuid\Exception\InvalidUuidStringException;
 use Ramsey\Uuid\UuidInterface;
 
+use function bin2hex;
+use function sprintf;
+use function substr;
+use function substr_replace;
+
 /**
  * TimestampFirstCombCodec encodes and decodes COMBs, with the timestamp as the
  * first 48 bits
diff --git a/src/Converter/Time/GenericTimeConverter.php b/src/Converter/Time/GenericTimeConverter.php
index bc506eb..6fab086 100644
--- a/src/Converter/Time/GenericTimeConverter.php
+++ b/src/Converter/Time/GenericTimeConverter.php
@@ -21,6 +21,11 @@ use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Type\IntegerValue;
 use Ramsey\Uuid\Type\Time;
 
+use function explode;
+use function str_pad;
+
+use const STR_PAD_LEFT;
+
 /**
  * GenericTimeConverter uses the provided calculator to calculate and convert
  * time values
diff --git a/src/Converter/Time/PhpTimeConverter.php b/src/Converter/Time/PhpTimeConverter.php
index e924216..1b1e198 100644
--- a/src/Converter/Time/PhpTimeConverter.php
+++ b/src/Converter/Time/PhpTimeConverter.php
@@ -21,6 +21,18 @@ use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Type\IntegerValue;
 use Ramsey\Uuid\Type\Time;
 
+use function count;
+use function dechex;
+use function explode;
+use function ini_get;
+use function is_float;
+use function is_int;
+use function str_pad;
+use function strlen;
+
+use const STR_PAD_LEFT;
+use const STR_PAD_RIGHT;
+
 /**
  * PhpTimeConverter uses built-in PHP functions and standard math operations
  * available to the PHP programming language to provide facilities for
diff --git a/src/DeprecatedUuidMethodsTrait.php b/src/DeprecatedUuidMethodsTrait.php
index 23fec83..5c1cfcb 100644
--- a/src/DeprecatedUuidMethodsTrait.php
+++ b/src/DeprecatedUuidMethodsTrait.php
@@ -23,6 +23,11 @@ use Ramsey\Uuid\Exception\UnsupportedOperationException;
 use Ramsey\Uuid\Rfc4122\FieldsInterface as Rfc4122FieldsInterface;
 use Throwable;
 
+use function str_pad;
+use function substr;
+
+use const STR_PAD_LEFT;
+
 /**
  * This trait encapsulates deprecated methods for ramsey/uuid; this trait and
  * its methods will be removed in ramsey/uuid 5.0.0.
diff --git a/src/FeatureSet.php b/src/FeatureSet.php
index ed82a23..4f23171 100644
--- a/src/FeatureSet.php
+++ b/src/FeatureSet.php
@@ -47,6 +47,8 @@ use Ramsey\Uuid\Rfc4122\UuidBuilder as Rfc4122UuidBuilder;
 use Ramsey\Uuid\Validator\GenericValidator;
 use Ramsey\Uuid\Validator\ValidatorInterface;
 
+use const PHP_INT_SIZE;
+
 /**
  * FeatureSet detects and exposes available features in the current environment
  *
diff --git a/src/Generator/CombGenerator.php b/src/Generator/CombGenerator.php
index cd94503..88ae6ea 100644
--- a/src/Generator/CombGenerator.php
+++ b/src/Generator/CombGenerator.php
@@ -17,6 +17,15 @@ namespace Ramsey\Uuid\Generator;
 use Ramsey\Uuid\Converter\NumberConverterInterface;
 use Ramsey\Uuid\Exception\InvalidArgumentException;
 
+use function bin2hex;
+use function explode;
+use function hex2bin;
+use function microtime;
+use function str_pad;
+use function substr;
+
+use const STR_PAD_LEFT;
+
 /**
  * CombGenerator generates COMBs (combined UUID/timestamp)
  *
diff --git a/src/Generator/DceSecurityGenerator.php b/src/Generator/DceSecurityGenerator.php
index 91bfc4e..c7c08de 100644
--- a/src/Generator/DceSecurityGenerator.php
+++ b/src/Generator/DceSecurityGenerator.php
@@ -21,6 +21,14 @@ use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Type\IntegerValue;
 use Ramsey\Uuid\Uuid;
 
+use function hex2bin;
+use function in_array;
+use function pack;
+use function str_pad;
+use function substr_replace;
+
+use const STR_PAD_LEFT;
+
 /**
  * DceSecurityGenerator generates strings of binary data based on a local
  * domain, local identifier, node ID, clock sequence, and the current time
diff --git a/src/Generator/DefaultTimeGenerator.php b/src/Generator/DefaultTimeGenerator.php
index 66c23bc..f82d663 100644
--- a/src/Generator/DefaultTimeGenerator.php
+++ b/src/Generator/DefaultTimeGenerator.php
@@ -22,6 +22,17 @@ use Ramsey\Uuid\Provider\NodeProviderInterface;
 use Ramsey\Uuid\Provider\TimeProviderInterface;
 use Throwable;
 
+use function ctype_xdigit;
+use function dechex;
+use function hex2bin;
+use function is_int;
+use function pack;
+use function random_int;
+use function str_pad;
+use function strlen;
+
+use const STR_PAD_LEFT;
+
 /**
  * DefaultTimeGenerator generates strings of binary data based on a node ID,
  * clock sequence, and the current time
diff --git a/src/Generator/RandomBytesGenerator.php b/src/Generator/RandomBytesGenerator.php
index e6e9a19..dcf6ad8 100644
--- a/src/Generator/RandomBytesGenerator.php
+++ b/src/Generator/RandomBytesGenerator.php
@@ -16,6 +16,8 @@ namespace Ramsey\Uuid\Generator;
 
 use Ramsey\Uuid\Exception\RandomSourceException;
 
+use function random_bytes;
+
 /**
  * RandomBytesGenerator generates strings of random binary data using the
  * built-in `random_bytes()` PHP function
diff --git a/src/Guid/Fields.php b/src/Guid/Fields.php
index d396a97..ab2d787 100644
--- a/src/Guid/Fields.php
+++ b/src/Guid/Fields.php
@@ -23,6 +23,18 @@ use Ramsey\Uuid\Rfc4122\VersionTrait;
 use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Uuid;
 
+use function bin2hex;
+use function dechex;
+use function hexdec;
+use function pack;
+use function sprintf;
+use function str_pad;
+use function strlen;
+use function substr;
+use function unpack;
+
+use const STR_PAD_LEFT;
+
 /**
  * GUIDs are comprised of a set of named fields, according to RFC 4122
  *
diff --git a/src/Nonstandard/Fields.php b/src/Nonstandard/Fields.php
index 40f9af1..927bc6a 100644
--- a/src/Nonstandard/Fields.php
+++ b/src/Nonstandard/Fields.php
@@ -20,6 +20,16 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface;
 use Ramsey\Uuid\Rfc4122\VariantTrait;
 use Ramsey\Uuid\Type\Hexadecimal;
 
+use function bin2hex;
+use function dechex;
+use function hexdec;
+use function sprintf;
+use function str_pad;
+use function strlen;
+use function substr;
+
+use const STR_PAD_LEFT;
+
 /**
  * Nonstandard UUID fields do not conform to the RFC 4122 standard
  *
diff --git a/src/Provider/Dce/SystemDceSecurityProvider.php b/src/Provider/Dce/SystemDceSecurityProvider.php
index ce78104..18f0d5e 100644
--- a/src/Provider/Dce/SystemDceSecurityProvider.php
+++ b/src/Provider/Dce/SystemDceSecurityProvider.php
@@ -18,6 +18,21 @@ use Ramsey\Uuid\Exception\DceSecurityException;
 use Ramsey\Uuid\Provider\DceSecurityProviderInterface;
 use Ramsey\Uuid\Type\IntegerValue;
 
+use function constant;
+use function escapeshellarg;
+use function ini_get;
+use function preg_split;
+use function shell_exec;
+use function str_getcsv;
+use function strpos;
+use function strrpos;
+use function strtolower;
+use function strtoupper;
+use function substr;
+use function trim;
+
+use const PREG_SPLIT_NO_EMPTY;
+
 /**
  * SystemDceSecurityProvider retrieves the user or group identifiers from the system
  */
diff --git a/src/Provider/Node/RandomNodeProvider.php b/src/Provider/Node/RandomNodeProvider.php
index 26c3768..e4c10e7 100644
--- a/src/Provider/Node/RandomNodeProvider.php
+++ b/src/Provider/Node/RandomNodeProvider.php
@@ -17,6 +17,16 @@ namespace Ramsey\Uuid\Provider\Node;
 use Ramsey\Uuid\Exception\RandomSourceException;
 use Ramsey\Uuid\Provider\NodeProviderInterface;
 
+use function bin2hex;
+use function dechex;
+use function hex2bin;
+use function hexdec;
+use function random_bytes;
+use function str_pad;
+use function substr;
+
+use const STR_PAD_LEFT;
+
 /**
  * RandomNodeProvider generates a random node ID
  *
diff --git a/src/Provider/Node/SystemNodeProvider.php b/src/Provider/Node/SystemNodeProvider.php
index dba0ad1..9c19c45 100644
--- a/src/Provider/Node/SystemNodeProvider.php
+++ b/src/Provider/Node/SystemNodeProvider.php
@@ -16,6 +16,31 @@ namespace Ramsey\Uuid\Provider\Node;
 
 use Ramsey\Uuid\Provider\NodeProviderInterface;
 
+use function array_filter;
+use function array_map;
+use function array_walk;
+use function constant;
+use function count;
+use function file_get_contents;
+use function glob;
+use function ini_get;
+use function is_array;
+use function is_readable;
+use function ob_get_clean;
+use function ob_start;
+use function passthru;
+use function preg_match;
+use function preg_match_all;
+use function reset;
+use function str_replace;
+use function strpos;
+use function strtolower;
+use function strtoupper;
+use function substr;
+
+use const GLOB_NOSORT;
+use const PREG_PATTERN_ORDER;
+
 /**
  * SystemNodeProvider retrieves the system node ID, if possible
  *
diff --git a/src/Provider/Time/FixedTimeProvider.php b/src/Provider/Time/FixedTimeProvider.php
index c60603d..850f38a 100644
--- a/src/Provider/Time/FixedTimeProvider.php
+++ b/src/Provider/Time/FixedTimeProvider.php
@@ -18,6 +18,8 @@ use Ramsey\Uuid\Exception\InvalidArgumentException;
 use Ramsey\Uuid\Provider\TimeProviderInterface;
 use Ramsey\Uuid\Type\Time;
 
+use function array_key_exists;
+
 /**
  * FixedTimeProvider uses an known time to provide the time
  *
diff --git a/src/Provider/Time/SystemTimeProvider.php b/src/Provider/Time/SystemTimeProvider.php
index 93ff01f..8958c48 100644
--- a/src/Provider/Time/SystemTimeProvider.php
+++ b/src/Provider/Time/SystemTimeProvider.php
@@ -17,6 +17,8 @@ namespace Ramsey\Uuid\Provider\Time;
 use Ramsey\Uuid\Provider\TimeProviderInterface;
 use Ramsey\Uuid\Type\Time;
 
+use function gettimeofday;
+
 /**
  * SystemTimeProvider retrieves the current time using built-in PHP functions
  */
diff --git a/src/Rfc4122/Fields.php b/src/Rfc4122/Fields.php
index a6a5ee0..9d7a589 100644
--- a/src/Rfc4122/Fields.php
+++ b/src/Rfc4122/Fields.php
@@ -19,6 +19,17 @@ use Ramsey\Uuid\Fields\SerializableFieldsTrait;
 use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Uuid;
 
+use function bin2hex;
+use function dechex;
+use function hexdec;
+use function sprintf;
+use function str_pad;
+use function strlen;
+use function substr;
+use function unpack;
+
+use const STR_PAD_LEFT;
+
 /**
  * RFC 4122 variant UUIDs are comprised of a set of named fields
  *
diff --git a/src/Rfc4122/NilTrait.php b/src/Rfc4122/NilTrait.php
index 94294e4..f740f4f 100644
--- a/src/Rfc4122/NilTrait.php
+++ b/src/Rfc4122/NilTrait.php
@@ -14,6 +14,8 @@ declare(strict_types=1);
 
 namespace Ramsey\Uuid\Rfc4122;
 
+use function hex2bin;
+
 /**
  * Provides common functionality for nil UUIDs
  *
diff --git a/src/Rfc4122/UuidV1.php b/src/Rfc4122/UuidV1.php
index 7356c3a..4989915 100644
--- a/src/Rfc4122/UuidV1.php
+++ b/src/Rfc4122/UuidV1.php
@@ -25,6 +25,10 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface as Rfc4122FieldsInterface;
 use Ramsey\Uuid\Uuid;
 use Throwable;
 
+use function str_pad;
+
+use const STR_PAD_LEFT;
+
 /**
  * Time-based, or version 1, UUIDs include timestamp, clock sequence, and node
  * values that are combined into a 128-bit unsigned integer
diff --git a/src/Rfc4122/Validator.php b/src/Rfc4122/Validator.php
index 2df2c68..ad6d6f0 100644
--- a/src/Rfc4122/Validator.php
+++ b/src/Rfc4122/Validator.php
@@ -17,6 +17,9 @@ namespace Ramsey\Uuid\Rfc4122;
 use Ramsey\Uuid\Uuid;
 use Ramsey\Uuid\Validator\ValidatorInterface;
 
+use function preg_match;
+use function str_replace;
+
 /**
  * Rfc4122\Validator validates strings as UUIDs of the RFC 4122 variant
  */
diff --git a/src/Rfc4122/VariantTrait.php b/src/Rfc4122/VariantTrait.php
index 01726b4..c32a8ce 100644
--- a/src/Rfc4122/VariantTrait.php
+++ b/src/Rfc4122/VariantTrait.php
@@ -17,6 +17,15 @@ namespace Ramsey\Uuid\Rfc4122;
 use Ramsey\Uuid\Exception\InvalidBytesException;
 use Ramsey\Uuid\Uuid;
 
+use function decbin;
+use function str_pad;
+use function strlen;
+use function strpos;
+use function substr;
+use function unpack;
+
+use const STR_PAD_LEFT;
+
 /**
  * Provides common functionality for handling the variant, as defined by RFC 4122
  *
diff --git a/src/Type/Decimal.php b/src/Type/Decimal.php
index c072c06..a64eabd 100644
--- a/src/Type/Decimal.php
+++ b/src/Type/Decimal.php
@@ -16,6 +16,8 @@ namespace Ramsey\Uuid\Type;
 
 use Ramsey\Uuid\Exception\InvalidArgumentException;
 
+use function is_numeric;
+
 /**
  * A value object representing a decimal
  *
diff --git a/src/Type/Hexadecimal.php b/src/Type/Hexadecimal.php
index ee3e952..2d22fc6 100644
--- a/src/Type/Hexadecimal.php
+++ b/src/Type/Hexadecimal.php
@@ -17,6 +17,9 @@ namespace Ramsey\Uuid\Type;
 use Ramsey\Uuid\Exception\InvalidArgumentException;
 
 use function ctype_xdigit;
+use function strpos;
+use function strtolower;
+use function substr;
 
 /**
  * A value object representing a hexadecimal number
diff --git a/src/Type/IntegerValue.php b/src/Type/IntegerValue.php
index 2c47453..4735831 100644
--- a/src/Type/IntegerValue.php
+++ b/src/Type/IntegerValue.php
@@ -17,6 +17,9 @@ namespace Ramsey\Uuid\Type;
 use Ramsey\Uuid\Exception\InvalidArgumentException;
 
 use function ctype_digit;
+use function ltrim;
+use function strpos;
+use function substr;
 
 /**
  * A value object representing an integer
diff --git a/src/Uuid.php b/src/Uuid.php
index e4489fe..10de927 100644
--- a/src/Uuid.php
+++ b/src/Uuid.php
@@ -23,6 +23,9 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface as Rfc4122FieldsInterface;
 use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Type\IntegerValue;
 
+use function str_replace;
+use function strcmp;
+
 /**
  * Represents a RFC 4122 universally unique identifier (UUID)
  *
diff --git a/src/UuidFactory.php b/src/UuidFactory.php
index d07da29..93fcb94 100644
--- a/src/UuidFactory.php
+++ b/src/UuidFactory.php
@@ -30,6 +30,16 @@ use Ramsey\Uuid\Type\IntegerValue;
 use Ramsey\Uuid\Type\Time;
 use Ramsey\Uuid\Validator\ValidatorInterface;
 
+use function hash;
+use function pack;
+use function str_pad;
+use function strtolower;
+use function substr;
+use function substr_replace;
+use function unpack;
+
+use const STR_PAD_LEFT;
+
 class UuidFactory implements UuidFactoryInterface
 {
     /**
diff --git a/src/Validator/GenericValidator.php b/src/Validator/GenericValidator.php
index 87054f7..cb7b486 100644
--- a/src/Validator/GenericValidator.php
+++ b/src/Validator/GenericValidator.php
@@ -16,6 +16,9 @@ namespace Ramsey\Uuid\Validator;
 
 use Ramsey\Uuid\Uuid;
 
+use function preg_match;
+use function str_replace;
+
 /**
  * GenericValidator validates strings as UUIDs of any variant
  */
diff --git a/tests/BinaryUtilsTest.php b/tests/BinaryUtilsTest.php
index 739c956..0497bfd 100644
--- a/tests/BinaryUtilsTest.php
+++ b/tests/BinaryUtilsTest.php
@@ -6,6 +6,8 @@ namespace Ramsey\Uuid\Test;
 
 use Ramsey\Uuid\BinaryUtils;
 
+use function dechex;
+
 class BinaryUtilsTest extends TestCase
 {
     /**
diff --git a/tests/Builder/DefaultUuidBuilderTest.php b/tests/Builder/DefaultUuidBuilderTest.php
index 5325b1c..f64d7cb 100644
--- a/tests/Builder/DefaultUuidBuilderTest.php
+++ b/tests/Builder/DefaultUuidBuilderTest.php
@@ -12,6 +12,9 @@ use Ramsey\Uuid\Converter\TimeConverterInterface;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Uuid;
 
+use function hex2bin;
+use function implode;
+
 class DefaultUuidBuilderTest extends TestCase
 {
     public function testBuildCreatesUuid(): void
diff --git a/tests/Codec/GuidStringCodecTest.php b/tests/Codec/GuidStringCodecTest.php
index e766fa8..c70d572 100644
--- a/tests/Codec/GuidStringCodecTest.php
+++ b/tests/Codec/GuidStringCodecTest.php
@@ -16,6 +16,9 @@ use Ramsey\Uuid\Guid\GuidBuilder;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function pack;
+
 class GuidStringCodecTest extends TestCase
 {
     /**
diff --git a/tests/Codec/OrderedTimeCodecTest.php b/tests/Codec/OrderedTimeCodecTest.php
index 614e7bb..fbdddaf 100644
--- a/tests/Codec/OrderedTimeCodecTest.php
+++ b/tests/Codec/OrderedTimeCodecTest.php
@@ -23,6 +23,10 @@ use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\UuidFactory;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function pack;
+use function str_replace;
+
 class OrderedTimeCodecTest extends TestCase
 {
     /**
diff --git a/tests/Codec/StringCodecTest.php b/tests/Codec/StringCodecTest.php
index f457d0a..3ded53c 100644
--- a/tests/Codec/StringCodecTest.php
+++ b/tests/Codec/StringCodecTest.php
@@ -13,6 +13,10 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function implode;
+use function pack;
+
 class StringCodecTest extends TestCase
 {
     /**
diff --git a/tests/Converter/Time/BigNumberTimeConverterTest.php b/tests/Converter/Time/BigNumberTimeConverterTest.php
index cd6f871..f1703c5 100644
--- a/tests/Converter/Time/BigNumberTimeConverterTest.php
+++ b/tests/Converter/Time/BigNumberTimeConverterTest.php
@@ -10,6 +10,8 @@ use Ramsey\Uuid\Exception\InvalidArgumentException;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 
+use function sprintf;
+
 class BigNumberTimeConverterTest extends TestCase
 {
     public function testCalculateTimeReturnsArrayOfTimeSegments(): void
diff --git a/tests/Converter/Time/PhpTimeConverterTest.php b/tests/Converter/Time/PhpTimeConverterTest.php
index 0bc09aa..eae5599 100644
--- a/tests/Converter/Time/PhpTimeConverterTest.php
+++ b/tests/Converter/Time/PhpTimeConverterTest.php
@@ -13,6 +13,8 @@ use Ramsey\Uuid\Math\BrickMathCalculator;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 
+use function sprintf;
+
 class PhpTimeConverterTest extends TestCase
 {
     public function testCalculateTimeReturnsArrayOfTimeSegments(): void
diff --git a/tests/Encoder/TimestampFirstCombCodecTest.php b/tests/Encoder/TimestampFirstCombCodecTest.php
index 3544fff..875695f 100644
--- a/tests/Encoder/TimestampFirstCombCodecTest.php
+++ b/tests/Encoder/TimestampFirstCombCodecTest.php
@@ -13,6 +13,9 @@ use Ramsey\Uuid\Rfc4122\Fields;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function implode;
+
 class TimestampFirstCombCodecTest extends TestCase
 {
     /**
diff --git a/tests/Encoder/TimestampLastCombCodecTest.php b/tests/Encoder/TimestampLastCombCodecTest.php
index 4c81098..5bd41c2 100644
--- a/tests/Encoder/TimestampLastCombCodecTest.php
+++ b/tests/Encoder/TimestampLastCombCodecTest.php
@@ -14,6 +14,9 @@ use Ramsey\Uuid\Rfc4122\FieldsInterface;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\UuidInterface;
 
+use function hex2bin;
+use function implode;
+
 class TimestampLastCombCodecTest extends TestCase
 {
     /**
diff --git a/tests/Generator/CombGeneratorTest.php b/tests/Generator/CombGeneratorTest.php
index 2f9655c..ee0de3f 100644
--- a/tests/Generator/CombGeneratorTest.php
+++ b/tests/Generator/CombGeneratorTest.php
@@ -13,6 +13,13 @@ use Ramsey\Uuid\Generator\CombGenerator;
 use Ramsey\Uuid\Generator\RandomGeneratorInterface;
 use Ramsey\Uuid\Test\TestCase;
 
+use function bin2hex;
+use function dechex;
+use function hex2bin;
+use function str_pad;
+
+use const STR_PAD_LEFT;
+
 class CombGeneratorTest extends TestCase
 {
     /**
diff --git a/tests/Generator/DceSecurityGeneratorTest.php b/tests/Generator/DceSecurityGeneratorTest.php
index 751ef18..32f9bb3 100644
--- a/tests/Generator/DceSecurityGeneratorTest.php
+++ b/tests/Generator/DceSecurityGeneratorTest.php
@@ -22,6 +22,9 @@ use Ramsey\Uuid\Type\IntegerValue;
 use Ramsey\Uuid\Type\Time;
 use Ramsey\Uuid\Uuid;
 
+use function bin2hex;
+use function substr;
+
 class DceSecurityGeneratorTest extends TestCase
 {
     /**
diff --git a/tests/Generator/DefaultTimeGeneratorTest.php b/tests/Generator/DefaultTimeGeneratorTest.php
index bac066c..4715117 100644
--- a/tests/Generator/DefaultTimeGeneratorTest.php
+++ b/tests/Generator/DefaultTimeGeneratorTest.php
@@ -22,6 +22,8 @@ use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Type\Time;
 
+use function hex2bin;
+
 class DefaultTimeGeneratorTest extends TestCase
 {
     /**
diff --git a/tests/Generator/RandomBytesGeneratorTest.php b/tests/Generator/RandomBytesGeneratorTest.php
index 32b6d8b..83b8fbc 100644
--- a/tests/Generator/RandomBytesGeneratorTest.php
+++ b/tests/Generator/RandomBytesGeneratorTest.php
@@ -10,6 +10,8 @@ use Ramsey\Uuid\Exception\RandomSourceException;
 use Ramsey\Uuid\Generator\RandomBytesGenerator;
 use Ramsey\Uuid\Test\TestCase;
 
+use function hex2bin;
+
 class RandomBytesGeneratorTest extends TestCase
 {
     /**
diff --git a/tests/Guid/FieldsTest.php b/tests/Guid/FieldsTest.php
index 0e68215..3e39c59 100644
--- a/tests/Guid/FieldsTest.php
+++ b/tests/Guid/FieldsTest.php
@@ -9,6 +9,10 @@ use Ramsey\Uuid\Guid\Fields;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 
+use function hex2bin;
+use function serialize;
+use function unserialize;
+
 class FieldsTest extends TestCase
 {
     public function testConstructorThrowsExceptionIfNotSixteenByteString(): void
diff --git a/tests/Nonstandard/FieldsTest.php b/tests/Nonstandard/FieldsTest.php
index 6523177..842cd8a 100644
--- a/tests/Nonstandard/FieldsTest.php
+++ b/tests/Nonstandard/FieldsTest.php
@@ -10,6 +10,11 @@ use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\Uuid;
 
+use function hex2bin;
+use function serialize;
+use function str_replace;
+use function unserialize;
+
 class FieldsTest extends TestCase
 {
     public function testConstructorThrowsExceptionIfNotSixteenByteString(): void
diff --git a/tests/Provider/Dce/SystemDceSecurityProviderTest.php b/tests/Provider/Dce/SystemDceSecurityProviderTest.php
index 092d14f..b129289 100644
--- a/tests/Provider/Dce/SystemDceSecurityProviderTest.php
+++ b/tests/Provider/Dce/SystemDceSecurityProviderTest.php
@@ -10,6 +10,8 @@ use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\IntegerValue;
 use phpmock\mockery\PHPMockery;
 
+use function array_merge;
+
 class SystemDceSecurityProviderTest extends TestCase
 {
     /**
diff --git a/tests/Provider/Node/RandomNodeProviderTest.php b/tests/Provider/Node/RandomNodeProviderTest.php
index 5d02785..93867cf 100644
--- a/tests/Provider/Node/RandomNodeProviderTest.php
+++ b/tests/Provider/Node/RandomNodeProviderTest.php
@@ -10,6 +10,12 @@ use Ramsey\Uuid\Exception\RandomSourceException;
 use Ramsey\Uuid\Provider\Node\RandomNodeProvider;
 use Ramsey\Uuid\Test\TestCase;
 
+use function bin2hex;
+use function hex2bin;
+use function hexdec;
+use function sprintf;
+use function substr;
+
 class RandomNodeProviderTest extends TestCase
 {
     protected function tearDown(): void
diff --git a/tests/Provider/Node/SystemNodeProviderTest.php b/tests/Provider/Node/SystemNodeProviderTest.php
index 86e940b..61a251f 100644
--- a/tests/Provider/Node/SystemNodeProviderTest.php
+++ b/tests/Provider/Node/SystemNodeProviderTest.php
@@ -10,6 +10,13 @@ use Ramsey\Uuid\Exception\InvalidArgumentException;
 use Ramsey\Uuid\Provider\Node\SystemNodeProvider;
 use Ramsey\Uuid\Test\TestCase;
 
+use function array_shift;
+use function array_walk;
+use function gettype;
+use function is_array;
+use function strlen;
+use function vsprintf;
+
 /**
  * Tests for the SystemNodeProvider class
  *
diff --git a/tests/Rfc4122/FieldsTest.php b/tests/Rfc4122/FieldsTest.php
index a79ee8a..0c57396 100644
--- a/tests/Rfc4122/FieldsTest.php
+++ b/tests/Rfc4122/FieldsTest.php
@@ -9,6 +9,11 @@ use Ramsey\Uuid\Rfc4122\Fields;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Type\Hexadecimal;
 
+use function hex2bin;
+use function serialize;
+use function str_replace;
+use function unserialize;
+
 class FieldsTest extends TestCase
 {
     public function testConstructorThrowsExceptionIfNotSixteenByteString(): void
diff --git a/tests/Rfc4122/UuidBuilderTest.php b/tests/Rfc4122/UuidBuilderTest.php
index 1fb2d30..ddcd055 100644
--- a/tests/Rfc4122/UuidBuilderTest.php
+++ b/tests/Rfc4122/UuidBuilderTest.php
@@ -18,6 +18,9 @@ use Ramsey\Uuid\Rfc4122\UuidV4;
 use Ramsey\Uuid\Rfc4122\UuidV5;
 use Ramsey\Uuid\Test\TestCase;
 
+use function hex2bin;
+use function str_replace;
+
 class UuidBuilderTest extends TestCase
 {
     /**
diff --git a/tests/Rfc4122/ValidatorTest.php b/tests/Rfc4122/ValidatorTest.php
index 54c943e..2203ba4 100644
--- a/tests/Rfc4122/ValidatorTest.php
+++ b/tests/Rfc4122/ValidatorTest.php
@@ -7,6 +7,10 @@ namespace Ramsey\Uuid\Test\Rfc4122;
 use Ramsey\Uuid\Rfc4122\Validator;
 use Ramsey\Uuid\Test\TestCase;
 
+use function array_merge;
+use function in_array;
+use function strtoupper;
+
 class ValidatorTest extends TestCase
 {
     /**
diff --git a/tests/Rfc4122/VariantTraitTest.php b/tests/Rfc4122/VariantTraitTest.php
index 08145f1..e5da177 100644
--- a/tests/Rfc4122/VariantTraitTest.php
+++ b/tests/Rfc4122/VariantTraitTest.php
@@ -9,6 +9,9 @@ use Ramsey\Uuid\Exception\InvalidBytesException;
 use Ramsey\Uuid\Rfc4122\VariantTrait;
 use Ramsey\Uuid\Test\TestCase;
 
+use function hex2bin;
+use function str_replace;
+
 class VariantTraitTest extends TestCase
 {
     /**
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 87a03b4..84228fe 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -8,6 +8,10 @@ use AspectMock\Test as AspectMock;
 use Mockery;
 use PHPUnit\Framework\TestCase as PhpUnitTestCase;
 
+use function current;
+use function pack;
+use function unpack;
+
 class TestCase extends PhpUnitTestCase
 {
     protected function tearDown(): void
diff --git a/tests/UuidFactoryTest.php b/tests/UuidFactoryTest.php
index 40154ef..edf2c92 100644
--- a/tests/UuidFactoryTest.php
+++ b/tests/UuidFactoryTest.php
@@ -23,6 +23,9 @@ use Ramsey\Uuid\Type\Hexadecimal;
 use Ramsey\Uuid\UuidFactory;
 use Ramsey\Uuid\Validator\ValidatorInterface;
 
+use function hex2bin;
+use function strtoupper;
+
 class UuidFactoryTest extends TestCase
 {
     public function testParsesUuidCorrectly(): void
diff --git a/tests/UuidTest.php b/tests/UuidTest.php
index d95f837..3502813 100644
--- a/tests/UuidTest.php
+++ b/tests/UuidTest.php
@@ -42,7 +42,20 @@ use Ramsey\Uuid\Validator\GenericValidator;
 use Ramsey\Uuid\Validator\ValidatorInterface;
 use stdClass;
 
+use function base64_decode;
+use function base64_encode;
+use function gmdate;
+use function hex2bin;
+use function json_encode;
+use function serialize;
+use function str_pad;
 use function strlen;
+use function strtotime;
+use function strtoupper;
+use function substr;
+use function uniqid;
+use function unserialize;
+use function usleep;
 
 class UuidTest extends TestCase
 {
diff --git a/tests/Validator/GenericValidatorTest.php b/tests/Validator/GenericValidatorTest.php
index 8e18860..59ba46c 100644
--- a/tests/Validator/GenericValidatorTest.php
+++ b/tests/Validator/GenericValidatorTest.php
@@ -7,6 +7,9 @@ namespace Ramsey\Uuid\Test\Validator;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Validator\GenericValidator;
 
+use function array_merge;
+use function strtoupper;
+
 class GenericValidatorTest extends TestCase
 {
     /**