diff --git a/src/AWS/CRT/Internal/Encoding.php b/src/AWS/CRT/Internal/Encoding.php
index 7fc93f4..75446fc 100644
--- a/src/AWS/CRT/Internal/Encoding.php
+++ b/src/AWS/CRT/Internal/Encoding.php
@@ -29,6 +29,9 @@ final class Encoding {
     }
 
     public static function encodeString($str) {
+        if (is_array($str)) {
+            $str = $str[0];
+        }
         return pack("Na*", strlen($str), $str);
     }
 }