diff --git a/src/SAML2/HTTPPost.php b/src/SAML2/HTTPPost.php
index b12cc4e22..88639dd3b 100644
--- a/src/SAML2/HTTPPost.php
+++ b/src/SAML2/HTTPPost.php
@@ -4,6 +4,8 @@
 
 namespace SAML2;
 
+use Webmozart\Assert\Assert;
+
 /**
  * Class which implements the HTTP-POST binding.
  *