diff --git a/src/MailChimp.php b/src/MailChimp.php
index e810836..7f57479 100644
--- a/src/MailChimp.php
+++ b/src/MailChimp.php
@@ -337,7 +337,13 @@ private function getHeadersAsArray($headersAsString)
                 continue;
             }
 
-            list($key, $value) = explode(':', $line);
+            if (strstr($line, ':')) {
+                list($key, $value) = explode(':', $line);
+            } else {
+                $key = null;
+                $value = $line;
+            }
+
             $value = ltrim($value);
 
             if ($key == 'Link') {