diff --git a/rwx/prj/sphinx.py b/rwx/prj/sphinx.py
index 290c5d9..4da1ebf 100644
--- a/rwx/prj/sphinx.py
+++ b/rwx/prj/sphinx.py
@@ -16,7 +16,7 @@ class SphinxProject(Project):
             "-E",
             "-j", "2",
             "-b", "html",
-            "-D", "project={}".format(self.name),
+            "-D", f"project={self.name}",
             "-D", "master_doc={}".format("index"),
             "-D", "html_theme={}".format("sphinx_rtd_theme"),
             "-c", self.root,