diff --git a/src/emacs/lean-syntax.el b/src/emacs/lean-syntax.el
index 5e416c3b29..e9e6fac814 100644
--- a/src/emacs/lean-syntax.el
+++ b/src/emacs/lean-syntax.el
@@ -20,7 +20,8 @@
     "attribute" "local" "set_option" "extends" "include" "omit" "classes"
     "instances" "coercions" "metaclasses" "raw" "migrate" "replacing"
     "calc" "have" "show" "suffices" "by" "in" "at" "do" "let" "forall" "Pi" "fun"
-    "exists" "if" "dif" "then" "else" "assume" "take" "obtain" "from" "aliases" "register_simp_ext")
+    "exists" "if" "dif" "then" "else" "assume" "take" "obtain" "from" "aliases" "register_simp_ext"
+    "mutual_definition" "mutual_inductive")
   "lean keywords ending with 'word' (not symbol)")
 (defconst lean-keywords1-regexp
   (eval `(rx word-start (or ,@lean-keywords1) word-end)))