diff --git a/src/proto/terminal.pro b/src/proto/terminal.pro
index a318fc8..e6914c0 100644
--- a/src/proto/terminal.pro
+++ b/src/proto/terminal.pro
@@ -5,6 +5,7 @@
 int term_write_session(FILE *fd, win_T *wp);
 int term_should_restore(buf_T *buf);
 void free_terminal(buf_T *buf);
+void free_unused_terminals(void);
 void write_to_term(buf_T *buffer, char_u *msg, channel_T *channel);
 int term_job_running(term_T *term);
 int term_none_open(term_T *term);