diff --git a/shm.c b/shm.c
index 005d030e..4c342ddf 100644
--- a/shm.c
+++ b/shm.c
@@ -509,6 +509,13 @@ err:
     abort();
 }
 
+void
+shm_did_not_use_buf(struct buffer *_buf)
+{
+    struct buffer_private *buf = (struct buffer_private *)_buf;
+    buf->busy = false;
+}
+
 void
 shm_get_many(struct buffer_chain *chain, size_t count,
              int widths[static count], int heights[static count],
diff --git a/shm.h b/shm.h
index 180c8525..bed4285c 100644
--- a/shm.h
+++ b/shm.h
@@ -66,6 +66,8 @@ void shm_get_many(
     int widths[static count], int heights[static count],
     struct buffer *bufs[static count]);
 
+void shm_did_not_use_buf(struct buffer *buf);
+
 bool shm_can_scroll(const struct buffer *buf);
 bool shm_scroll(struct buffer *buf, int rows,
                 int top_margin, int top_keep_rows,