diff --git a/config/initializers/slim.rb b/config/initializers/slim.rb
index 13cecd40..e87f2cf9 100644
--- a/config/initializers/slim.rb
+++ b/config/initializers/slim.rb
@@ -2,4 +2,4 @@
 Slim::Engine.set_default_options format: Settings.html.format.to_sym,
                                  pretty: Settings.html.pretty,
                                  sort_attrs: Settings.html.sort_attrs,
-                                 tab_size: Settings.html.tab_size
+                                 tabsize: Settings.html.tabsize
diff --git a/config/nembrot.yml b/config/nembrot.yml
index b67b8752..f481a95b 100644
--- a/config/nembrot.yml
+++ b/config/nembrot.yml
@@ -32,7 +32,7 @@ defaults: &defaults
   html:
     pretty: true
     sort_attrs: true
-    tab_size: 2
+    tabsize: 2
     format: html5
   notes:
     title_length: 40