diff --git a/doc/Sphinx/namelist.rst b/doc/Sphinx/namelist.rst
index d05d648a0..e0dbb15ec 100644
--- a/doc/Sphinx/namelist.rst
+++ b/doc/Sphinx/namelist.rst
@@ -709,7 +709,7 @@ External fields
 An external field can be applied using an ``ExtField`` block::
 
   ExtField(
-      fields = ["Ex"],
+      field = "Ex",
       profile = constant(0.01, xvacuum=0.1)
   )