diff --git a/modules/languages/siren-markdown.el b/modules/languages/siren-markdown.el
index f428a2c..7d34ad9 100644
--- a/modules/languages/siren-markdown.el
+++ b/modules/languages/siren-markdown.el
@@ -42,7 +42,8 @@
   :init
   (defun siren-markdown-mode-setup ()
     (setq-local markdown-asymmetric-header t
-                prettier-js-args '("--print-width" "80"
+                prettier-js-args '("--parser" "markdown"
+                                   "--print-width" "80"
                                    "--prose-wrap" "always")
                 whitespace-action nil)
 
diff --git a/modules/languages/siren-yaml.el b/modules/languages/siren-yaml.el
index 3591e99..a78112a 100644
--- a/modules/languages/siren-yaml.el
+++ b/modules/languages/siren-yaml.el
@@ -20,7 +20,8 @@
   :init
   (defun siren-yaml-mode-setup ()
     (run-hooks 'prog-mode-hook)
-    (setq tab-width 2)
+    (setq tab-width 2
+          prettier-js-args '("--parser" "yaml"))
     (prettier-js-mode)
     (subword-mode +1)))