diff --git a/filesetup.c b/filesetup.c
index f0e3b34..7669d70 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -1230,6 +1230,13 @@
 
 	set_already_allocated(file_name);
 
+	/*
+	 * For adding files after the fact - if openfiles= isn't
+	 * given as an option, ensure we allow at least one file open
+	 */
+	if (!td->o.open_files)
+		td->o.open_files = 1;
+
 	dprint(FD_FILE, "file %p \"%s\" added at %d\n", f, f->file_name,
 							cur_files);