diff --git a/tox.ini b/tox.ini
index 8a30566..ee01557 100644
--- a/tox.ini
+++ b/tox.ini
@@ -42,10 +42,10 @@ commands =
 [testenv:pdf-docs]
 deps = {[testenv:docs]deps}
 whitelist_externals =
-  make
+    make
 commands =
-  sphinx-build -W --keep-going -b latex doc/source doc/build/pdf
-  make -C doc/build/pdf
+    sphinx-build -W --keep-going -b latex doc/source doc/build/pdf
+    make -C doc/build/pdf
 
 [doc8]
 # Settings for doc8: