diff --git a/src/vim9class.c b/src/vim9class.c
index d8813c6..87b4d45 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -2646,7 +2646,7 @@
  * Type aliases (:type)
  */
 
-    void
+    static void
 typealias_free(typealias_T *ta)
 {
     // ta->ta_type is freed in clear_type_list()