diff --git a/CHANGELOG.md b/CHANGELOG.md
index 84dc0d1..8b1cd9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Change Log
 
+## UNRELEASED
+
+### Fixed
+
+- Cast max age header to integer in order to get valid expiration value.
 
 ## 1.0.0 - 2016-05-05
 
diff --git a/src/CachePlugin.php b/src/CachePlugin.php
index 24bf5c7..dbb3bab 100644
--- a/src/CachePlugin.php
+++ b/src/CachePlugin.php
@@ -174,7 +174,7 @@ private function getMaxAge(ResponseInterface $response)
                 return $maxAge - ((int) $age);
             }
 
-            return $maxAge;
+            return (int) $maxAge;
         }
 
         // check for ttl in the Expires header