diff --git a/src/tsm/libtsm-int.h b/src/tsm/libtsm-int.h
index dbc7924..7ae9bf4 100644
--- a/src/tsm/libtsm-int.h
+++ b/src/tsm/libtsm-int.h
@@ -152,6 +152,8 @@ struct tsm_screen {
 };
 
 void screen_cell_init(struct tsm_screen *con, struct cell *cell);
+void screen_fill(struct tsm_screen *con, tsm_symbol_t ch,
+		 const struct tsm_screen_attr *attr);
 
 void tsm_screen_set_opts(struct tsm_screen *scr, unsigned int opts);
 void tsm_screen_reset_opts(struct tsm_screen *scr, unsigned int opts);
diff --git a/src/tsm/tsm-screen.c b/src/tsm/tsm-screen.c
index 2004d9f..6521c11 100644
--- a/src/tsm/tsm-screen.c
+++ b/src/tsm/tsm-screen.c
@@ -1604,3 +1604,32 @@ void tsm_screen_erase_screen(struct tsm_screen *con, bool protect)
 	screen_erase_region(con, 0, 0, con->size_x - 1, con->size_y - 1,
 			     protect);
 }
+
+void screen_fill(struct tsm_screen *con, tsm_symbol_t ch,
+		     const struct tsm_screen_attr *attr)
+{
+	unsigned int len, x, y;
+	struct line *line;
+	struct cell cell;
+
+	if (!con)
+		return;
+
+	len = tsm_symbol_get_width(con->sym_table, ch);
+	if (len != 1)
+		return;
+
+	screen_inc_age(con);
+
+	cell.ch = ch;
+	cell.width = len;
+	memcpy(&cell.attr, attr, sizeof(cell.attr));
+	cell.age = con->age_cnt;
+
+	for (y = 0; y < con->size_y; ++y) {
+		line = con->lines[y];
+		for (x = 0; x < con->size_x; ++x) {
+			memcpy(&line->cells[x], &cell, sizeof(line->cells[x]));
+		}
+	}
+}
diff --git a/src/tsm/tsm-vte.c b/src/tsm/tsm-vte.c
index 1cfe402..fcc7ee4 100644
--- a/src/tsm/tsm-vte.c
+++ b/src/tsm/tsm-vte.c
@@ -110,6 +110,7 @@ enum parser_action {
 #define CSI_PLUS	0x0100		/* CSI: + */
 #define CSI_POPEN	0x0200		/* CSI: ( */
 #define CSI_PCLOSE	0x0400		/* CSI: ) */
+#define CSI_HASH	0x0800		/* CSI: # */
 
 /* max CSI arguments */
 #define CSI_ARG_MAX 16
@@ -918,6 +919,9 @@ static void do_collect(struct tsm_vte *vte, uint32_t data)
 	case ')':
 		vte->csi_flags |= CSI_PCLOSE;
 		break;
+	case '#':
+		vte->csi_flags |= CSI_HASH;
+		break;
 	}
 }
 
@@ -1053,6 +1057,18 @@ static void do_esc(struct tsm_vte *vte, uint32_t data)
 			return;
 		}
 		break;
+	case '8':
+		if (vte->csi_flags & CSI_HASH) {
+			/* DECALN */
+			/* DEC Screen Alignment Test */
+			vte->flags &= ~FLAG_ORIGIN_MODE;
+			tsm_screen_reset_flags(vte->con, TSM_SCREEN_REL_ORIGIN);
+			screen_fill(vte->con, 'E', &vte->def_attr);
+			tsm_screen_move_to(vte->con, 0, 0);
+			tsm_screen_set_margins(vte->con, 1, vte->con->size_y);
+			return;
+		}
+		break;
 	}
 
 	/* everything below is only valid without CSI flags */
diff --git a/test/test_common.h b/test/test_common.h
index ed30c1f..f018274 100644
--- a/test/test_common.h
+++ b/test/test_common.h
@@ -90,7 +90,7 @@ static inline int test_run_suite(Suite *s)
 	SRunner *sr;
 
 	sr = srunner_create(s);
-	srunner_run_all(sr, CK_NORMAL);
+	srunner_run_all(sr, CK_ENV);
 	ret = srunner_ntests_failed(sr);
 	srunner_free(sr);
 
diff --git a/test/test_vte.c b/test/test_vte.c
index 20bf370..c68ae6f 100644
--- a/test/test_vte.c
+++ b/test/test_vte.c
@@ -212,10 +212,91 @@ TEST_DEFINE_CASE(misc)
 	TEST(test_vte_backspace_key)
 TEST_END_CASE
 
+START_TEST(test_vte_DECALN)
+{
+	struct tsm_screen *screen;
+	struct tsm_vte *vte;
+	struct tsm_screen_attr attr;
+	const char *input;
+	unsigned int x, y, i;
+	tsm_age_t age;
+	int r;
+
+	r = tsm_screen_new(&screen, log_cb, NULL);
+	ck_assert_int_eq(r, 0);
+
+	tsm_screen_set_flags(screen, TSM_SCREEN_AUTO_WRAP);
+
+	i = 0;
+	for (y = 0; y < screen->size_y; ++y) {
+		for (x = 0; x < screen->size_x; ++x, ++i) {
+			attr.fr = i * 1;
+			attr.fg = i * 2;
+			attr.fb = i * 3;
+			attr.br = i * 4;
+			attr.bg = i * 5;
+			attr.bb = i * 6;
+			attr.bold = !!(i & 0x01);
+			attr.italic = !!(i & 0x02);
+			attr.underline = !!(i & 0x04);
+			attr.inverse = !!(i & 0x08);
+			attr.protect = !!(i & 0x10);
+			attr.blink = !!(i & 0x20);
+			tsm_screen_write(screen, '!' + (i % ('~' - '!')), &attr);
+		}
+	}
+
+	r = tsm_screen_set_margins(screen, 3, screen->size_y - 5);
+	ck_assert_int_eq(r, 0);
+
+	r = tsm_vte_new(&vte, screen, write_cb, NULL, log_cb, NULL);
+	ck_assert_int_eq(r, 0);
+
+	tsm_vte_get_def_attr(vte, &attr);
+	age = screen->age;
+
+	input = "\x1b[?6h" /* DECSET(DECOM) */ "\x1b#8" /* DECALN */;
+	tsm_vte_input(vte, input, strlen(input));
+
+	i = 0;
+	for (y = 0; y < screen->size_y; ++y) {
+		for (x = 0; x < screen->size_x; ++x, ++i) {
+			ck_assert_uint_eq(screen->lines[y]->cells[x].ch, 'E');
+			ck_assert_uint_eq(screen->lines[y]->cells[x].width, 1);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.fr, attr.fr);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.fg, attr.fg);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.fb, attr.fb);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.br, attr.br);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.bg, attr.bg);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.bb, attr.bb);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.bold, 0);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.italic, 0);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.underline, 0);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.inverse, 0);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.protect, 0);
+			ck_assert_uint_eq(screen->lines[y]->cells[x].attr.blink, 0);
+			ck_assert_uint_gt(screen->lines[y]->cells[x].age, age);
+		}
+	}
+
+	ck_assert_uint_ne(tsm_screen_get_flags(screen) & TSM_SCREEN_REL_ORIGIN, TSM_SCREEN_REL_ORIGIN);
+	ck_assert_uint_eq(tsm_screen_get_cursor_x(screen), 0);
+	ck_assert_uint_eq(tsm_screen_get_cursor_y(screen), 0);
+	ck_assert_uint_eq(screen->margin_top, 0);
+	ck_assert_uint_eq(screen->margin_bottom, screen->size_y - 1);
+	ck_assert_uint_lt(screen->cursor_x, screen->size_x);
+}
+END_TEST
+
+TEST_DEFINE_CASE(control_sequences)
+	TEST(test_vte_DECALN)
+TEST_END_CASE
+
 // clang-format off
 TEST_DEFINE(
 	TEST_SUITE(vte,
 		TEST_CASE(misc),
+		TEST_CASE(control_sequences),
 		TEST_END
 	)
 )