diff --git a/src/mbuf.c b/src/mbuf.c
index 9da7966..24aad00 100644
--- a/src/mbuf.c
+++ b/src/mbuf.c
@@ -29,7 +29,7 @@
     slirp->m_usedlist.qh_link = slirp->m_usedlist.qh_rlink = &slirp->m_usedlist;
 }
 
-void m_cleanup_list(struct quehead *list_head)
+static void m_cleanup_list(struct quehead *list_head)
 {
     struct mbuf *m, *next;