diff --git a/src/common/buf.c b/src/common/buf.c
index f6667418..f6bde97f 100644
--- a/src/common/buf.c
+++ b/src/common/buf.c
@@ -52,7 +52,7 @@ buf_expand_shell_variables(struct buf *s)
 	for (int i = 0 ; i < s->len ; i++) {
 		if (s->buf[i] == '$' && isvalid(s->buf[i+1])) {
 			/* expand environment variable */
-			environment_variable.len = 0;
+			buf_clear(&environment_variable);
 			buf_add(&environment_variable, s->buf + i + 1);
 			char *p = environment_variable.buf;
 			while (isvalid(*p)) {
diff --git a/src/osd.c b/src/osd.c
index 69feb4c8..ca53cec8 100644
--- a/src/osd.c
+++ b/src/osd.c
@@ -286,7 +286,7 @@ render_osd(struct server *server, cairo_t *cairo, int w, int h,
 		int nr_fields = wl_list_length(&rc.window_switcher.fields);
 		struct window_switcher_field *field;
 		wl_list_for_each(field, &rc.window_switcher.fields, link) {
-			buf.len = 0;
+			buf_clear(&buf);
 			cairo_move_to(cairo, x, y
 				+ theme->osd_window_switcher_item_padding_y
 				+ theme->osd_window_switcher_item_active_border_width);