diff --git a/config.vim b/config.vim
index 4e6ecae..21be71b 100644
--- a/config.vim
+++ b/config.vim
@@ -1,3 +1,9 @@
+function! s:setf(filetype) abort
+  if &filetype !=# a:filetype
+    let &filetype = a:filetype
+  endif
+endfunction
+
 " Enable jsx syntax by default
 if !exists('g:jsx_ext_required')
   let g:jsx_ext_required = 0
diff --git a/ftdetect/polyglot.vim b/ftdetect/polyglot.vim
index 3fb5107..830b1fb 100644
--- a/ftdetect/polyglot.vim
+++ b/ftdetect/polyglot.vim
@@ -1,3 +1,9 @@
+function! s:setf(filetype) abort
+  if &filetype !=# a:filetype
+    let &filetype = a:filetype
+  endif
+endfunction
+
 " Enable jsx syntax by default
 if !exists('g:jsx_ext_required')
   let g:jsx_ext_required = 0