diff --git a/requirements.txt b/requirements.txt
index 88bf614..1f07a0e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,7 @@
 pyopenssl
 requests
 lxml
+signxml
 
 # Opcional para NFS-e
 #-r requirements-nfse.txt