diff --git a/src/proto/os_unix.pro b/src/proto/os_unix.pro
index 3554040..d2f5e17 100644
--- a/src/proto/os_unix.pro
+++ b/src/proto/os_unix.pro
@@ -41,6 +41,7 @@
 int mch_can_exe __ARGS((char_u *name));
 int mch_nodetype __ARGS((char_u *name));
 void mch_early_init __ARGS((void));
+void mch_free_mem __ARGS((void));
 void mch_exit __ARGS((int r));
 void mch_settmode __ARGS((int tmode));
 void get_stty __ARGS((void));