diff --git a/sidecar/pyproject.toml b/sidecar/pyproject.toml
index 5e67812..9ddfbbf 100644
--- a/sidecar/pyproject.toml
+++ b/sidecar/pyproject.toml
@@ -6,7 +6,7 @@ requires-python = ">=3.12"
 dependencies = [
     "weasyprint==65.1",
     "Jinja2==3.1.4",
-    "factur-x==3.4",
+    "factur-x==4.2",
 ]
 
 [build-system]
diff --git a/sidecar/requirements.txt b/sidecar/requirements.txt
index e4a61fd..a778ba3 100644
--- a/sidecar/requirements.txt
+++ b/sidecar/requirements.txt
@@ -1,6 +1,6 @@
 weasyprint==65.1
 Jinja2==3.1.4
-factur-x==3.4
+factur-x==4.2
 lxml==5.3.0
 pypdf==5.1.0
 segno==1.6.1