diff --git a/src/evalvars.c b/src/evalvars.c
index 25d23c8..894ee28 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -669,6 +669,7 @@
  * ":let var ..= expr"		assignment command.
  * ":let [var1, var2] = expr"	unpack list.
  * ":let var =<< ..."		heredoc
+ * ":let var: string"		Vim9 declaration
  */
     void
 ex_let(exarg_T *eap)