--- a/io.c
+++ b/io.c
@@ -186,7 +186,16 @@ static void got_flist_entry_status(enum festatus status, const char *buf)
 	int ndx = IVAL(buf, 0);
 	struct file_list *flist = flist_for_ndx(ndx);
 
-	assert(flist != NULL);
+	if (flist == NULL) {
+		extern struct file_list *first_flist;
+		int start1 = first_flist ? first_flist->ndx_start : 0;
+		int start2 = first_flist ? first_flist->prev->ndx_start : 0;
+		int used = first_flist ? first_flist->prev->used : 0;
+		rprintf(FERROR,
+			"File index not found: %d (%d - %d)\n",
+			ndx, start1 - 1, start2 + used - 1);
+		exit_cleanup(RERR_PROTOCOL);
+	}
 
 	if (remove_source_files) {
 		active_filecnt--;