diff --git a/src/class.StringBuilder.php b/src/class.StringBuilder.php
index 1a1eed8..456f202 100644
--- a/src/class.StringBuilder.php
+++ b/src/class.StringBuilder.php
@@ -177,6 +177,9 @@ class StringBuilder {
      */
     public function setParts(array $parts=[]) : StringBuilder {
         $this->parts = $parts;
+        if($this->unique) {
+            $this->parts = array_unique($this->parts);
+        }
         return $this;
     }