diff --git a/src/PublicSuffixList.php b/src/PublicSuffixList.php
index 57ff6b9..70033f7 100644
--- a/src/PublicSuffixList.php
+++ b/src/PublicSuffixList.php
@@ -226,7 +226,7 @@ protected function readCachedPSL($url)
         $cacheFile = $this->getCacheFileName($url);
         if (file_exists($cacheFile)) {
             $cachedTree = file_get_contents($cacheFile);
-            if(PHP_VERSION_ID < 070000) {
+            if((int) PHP_VERSION_ID < 70000) {
                 return unserialize($cachedTree);
             }
             return unserialize($cachedTree, array('allowed_classes' => false));