diff --git a/src/Curl/ArrayUtil.php b/src/Curl/ArrayUtil.php
index cd83311..7c264a2 100644
--- a/src/Curl/ArrayUtil.php
+++ b/src/Curl/ArrayUtil.php
@@ -93,6 +93,8 @@ class ArrayUtil
                     } else {
                         if ($value instanceof \CURLFile) {
                             $return[$key] = $value;
+                        } elseif ($value instanceof \CURLStringFile) {
+                            $return[$key] = $value;
                         } else {
                             $return = array_merge(
                                 $return,
diff --git a/src/Curl/Curl.php b/src/Curl/Curl.php
index b41ec06..e8e9705 100644
--- a/src/Curl/Curl.php
+++ b/src/Curl/Curl.php
@@ -179,6 +179,8 @@ class Curl extends BaseCurl
                     }
                 } elseif ($value instanceof \CURLFile) {
                     $binary_data = true;
+                } elseif ($value instanceof \CURLStringFile) {
+                    $binary_data = true;
                 }
             }
         }