diff --git a/sphinx_doc_src/conf.py b/sphinx_doc_src/conf.py
index 808241b93..e2abca392 100644
--- a/sphinx_doc_src/conf.py
+++ b/sphinx_doc_src/conf.py
@@ -26,6 +26,8 @@ def setup(app):
         lexername='FishIndentLexer')
     lexers['fish-docs-samples'] = fish_indent_lexer
 
+# The default language to assume
+highlight_language = 'fish-docs-samples'
 
 # -- Path setup --------------------------------------------------------------