diff --git a/src/Key/Derivation/Scrypt.php b/src/Key/Derivation/Scrypt.php
index af04a4c..e5ff55b 100644
--- a/src/Key/Derivation/Scrypt.php
+++ b/src/Key/Derivation/Scrypt.php
@@ -329,7 +329,7 @@ protected static function integerify($b)
      */
     protected static function hex2bin($hex)
     {
-        if (version_compare(PHP_VERSION, '5.4') >= 0) {
+        if (PHP_VERSION_ID >= 50400) {
             return hex2bin($hex);
         }
         $len    = strlen($hex);
diff --git a/src/Password/Bcrypt.php b/src/Password/Bcrypt.php
index 8dfa3cb..bd7a519 100644
--- a/src/Password/Bcrypt.php
+++ b/src/Password/Bcrypt.php
@@ -83,7 +83,7 @@ public function create($password)
          * Check for security flaw in the bcrypt implementation used by crypt()
          * @see http://php.net/security/crypt_blowfish.php
          */
-        if ((version_compare(PHP_VERSION, '5.3.7') >= 0) && !$this->backwardCompatibility) {
+        if ((PHP_VERSION_ID >= 50307) && !$this->backwardCompatibility) {
             $prefix = '$2y$';
         } else {
             $prefix = '$2a$';