diff --git a/lib/Github/HttpClient/Message/ResponseMediator.php b/lib/Github/HttpClient/Message/ResponseMediator.php
index b9e8563d11a..7cc15035e84 100644
--- a/lib/Github/HttpClient/Message/ResponseMediator.php
+++ b/lib/Github/HttpClient/Message/ResponseMediator.php
@@ -56,9 +56,15 @@ public static function getPagination(ResponseInterface $response)
      */
     public static function getApiLimit(ResponseInterface $response)
     {
-        $remainingCalls = self::getHeader($response, 'X-RateLimit-Remaining');
+        $remainingCallsHeader = self::getHeader($response, 'X-RateLimit-Remaining');
 
-        if (null !== $remainingCalls && 1 > $remainingCalls) {
+        if (null === $remainingCallsHeader) {
+            return null;
+        }
+
+        $remainingCalls = (int) $remainingCallsHeader;
+
+        if (1 > $remainingCalls) {
             throw new ApiLimitExceedException((int) $remainingCalls);
         }