diff --git a/.readthedocs.yml b/.readthedocs.yml
index 2647c4ac2f3..55d6482b13b 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -9,6 +9,8 @@ python:
 
 build:
   os: ubuntu-20.04
+  tools:
+    python: "3"
   apt_packages:
     - inkscape
 
diff --git a/doc/en/conf.py b/doc/en/conf.py
index 00bcce97f70..ff91ccce0ef 100644
--- a/doc/en/conf.py
+++ b/doc/en/conf.py
@@ -43,7 +43,8 @@
 latex_engine = "lualatex"
 
 latex_elements = {
-    'preamble': dedent("""
+    "preamble": dedent(
+        """
         \directlua{
             luaotfload.add_fallback("fallbacks", {
                 "Noto Serif CJK SC:style=Regular;",
@@ -52,7 +53,8 @@
         }
 
         \setmainfont{FreeSerif}[RawFeature={fallback=fallbacks}]
-    """)
+        """
+    )
 }
 
 # -- General configuration -----------------------------------------------------