diff --git a/composer.json b/composer.json
index 952120c..518524d 100644
--- a/composer.json
+++ b/composer.json
@@ -26,6 +26,7 @@
     },
     "require": {
         "php": "^5.4 || ^7.0",
+        "ext-json": "*",
         "paragonie/random_compat": "^1.0|^2.0|9.99.99",
         "symfony/polyfill-ctype": "^1.8"
     },
diff --git a/src/UuidInterface.php b/src/UuidInterface.php
index ea3a46f..e1cea67 100644
--- a/src/UuidInterface.php
+++ b/src/UuidInterface.php
@@ -14,14 +14,18 @@
 
 namespace Ramsey\Uuid;
 
+use DateTime;
+use JsonSerializable;
 use Ramsey\Uuid\Converter\NumberConverterInterface;
+use Ramsey\Uuid\Exception\UnsatisfiedDependencyException;
 use Ramsey\Uuid\Exception\UnsupportedOperationException;
+use Serializable;
 
 /**
  * UuidInterface defines common functionality for all universally unique
  * identifiers (UUIDs)
  */
-interface UuidInterface extends \JsonSerializable, \Serializable
+interface UuidInterface extends JsonSerializable, Serializable
 {
     /**
      * Compares this UUID to the specified UUID.
@@ -121,9 +125,9 @@ interface UuidInterface extends \JsonSerializable, \Serializable
      * has version type 1. If this UUID is not a time-based UUID then
      * this method throws `UnsupportedOperationException`.
      *
-     * @return \DateTime A PHP DateTime representation of the date
+     * @return DateTime A PHP DateTime representation of the date
      * @throws UnsupportedOperationException If this UUID is not a version 1 UUID
-     * @throws \Ramsey\Uuid\Exception\UnsatisfiedDependencyException if called in a 32-bit system and
+     * @throws UnsatisfiedDependencyException if called in a 32-bit system and
      *     `Moontoast\Math\BigNumber` is not present
      */
     public function getDateTime();