diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5ff3353..b936a6b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -37,6 +37,22 @@ jobs:
       - run: make
       - run: make test-terminals
 
+  esctest:
+    runs-on: ubuntu-24.04
+    continue-on-error: true
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+      - run: sudo apt-get update && sudo apt-get install -y libncurses-dev python3-pexpect
+      - run: make
+      - run: git clone https://github.com/ThomasDickey/esctest2.git "$RUNNER_TEMP/esctest2"
+      - run: python3 test/run_esctest.py "$RUNNER_TEMP/esctest2" | tee esctest.txt
+      - if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: esctest
+          path: esctest.txt
+
   fuzz:
     runs-on: ubuntu-24.04
     steps:
diff --git a/test/run_esctest.py b/test/run_esctest.py
new file mode 100644
index 0000000..0a78799
--- /dev/null
+++ b/test/run_esctest.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+"""Run esctest (https://github.com/ThomasDickey/esctest2) inside dvtm.
+
+usage: run_esctest.py /path/to/esctest2 [extra esctest.py arguments]
+
+Prints the failing tests and a summary. Exits 0 even when tests fail, since
+this is a conformance report and not a gate.
+"""
+import os
+import re
+import shlex
+import sys
+import tempfile
+import time
+
+import pexpect
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+TIMEOUT = 1500
+
+
+def main():
+    esctest = os.path.join(os.path.abspath(sys.argv[1]), 'esctest')
+    extra = sys.argv[2:] or ['--max-vt-level', '4']
+    tmp = tempfile.mkdtemp()
+    out = os.path.join(tmp, 'out')
+    done = os.path.join(tmp, 'done')
+    log = os.path.join(tmp, 'log')
+    shell = os.path.join(tmp, 'shell')
+    cmd = ' '.join(['python3', 'esctest.py', '--expected-terminal', 'xterm',
+                    '--logfile', shlex.quote(log), '--no-print-logs'] +
+                   [shlex.quote(a) for a in extra])
+    with open(shell, 'w') as f:
+        f.write(f'#!/bin/sh\ncd {shlex.quote(esctest)}\n'
+                f'{cmd} 2> {shlex.quote(out)}\n'
+                f'touch {shlex.quote(done)}\nsleep 60\n')
+    os.chmod(shell, 0o755)
+
+    env = dict(os.environ, SHELL=shell, TERM='xterm')
+    p = pexpect.spawn(os.path.join(ROOT, 'dvtm'), env=env, dimensions=(25, 80))
+    start = time.time()
+    while not os.path.exists(done) and time.time() - start < TIMEOUT:
+        try:
+            p.read_nonblocking(65536, 0.5)
+        except (pexpect.TIMEOUT, pexpect.EOF):
+            pass
+    p.terminate(force=True)
+
+    if not os.path.exists(done):
+        print('esctest did not finish')
+        return 0
+    with open(out, errors='replace') as f:
+        text = f.read()
+    with open(log, errors='replace') as f:
+        failed = re.findall(r'^\*\*\* TEST (\S+) FAILED', f.read(), re.M)
+    for name in failed:
+        print('FAILED', name)
+    if not failed:
+        print(text[-2000:])
+    print(f'{len(failed)} test(s) failed')
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())
diff --git a/test/test-vt.c b/test/test-vt.c
index a8f96a6..3313758 100644
--- a/test/test-vt.c
+++ b/test/test-vt.c
@@ -164,6 +164,27 @@ static void test_device_attributes(void)
 	}
 }
 
+static void test_text_area_size(void)
+{
+	term = "XTWINOPS";
+	int fds[2];
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds))
+		abort();
+	Vt *t = vt_create(5, 10, 0);
+	t->pty = fds[0];
+	const char *query = "\033[18t\033[14t";
+	if (write(fds[1], query, strlen(query)) != (ssize_t)strlen(query))
+		abort();
+	vt_process(t);
+	fcntl(fds[1], F_SETFL, O_NONBLOCK);
+	char buf[32] = "";
+	ssize_t len = read(fds[1], buf, sizeof buf - 1);
+	buf[len > 0 ? len : 0] = '\0';
+	CHECK(!strcmp(buf, "\033[8;5;10t"));
+	close(fds[1]);
+	vt_destroy(t);
+}
+
 int main(void)
 {
 	setlocale(LC_CTYPE, "C.UTF-8");
@@ -191,6 +212,7 @@ int main(void)
 	setenv("TERMINFO", dir, 1);
 
 	test_device_attributes();
+	test_text_area_size();
 	test_term("xterm", COLOR_RED, COLOR_RED, COLOR_BLACK, COLOR_BLACK);
 	test_term("xterm-256color", 196, 196, 16, 16);
 	if (direct) {
diff --git a/vt.c b/vt.c
index 93f3691..9bd3a4d 100644
--- a/vt.c
+++ b/vt.c
@@ -1123,6 +1123,13 @@ static void interpret_csi(Vt *t)
 		if (param_count == 1 && csiparam[0] == 6)
 			send_curs(t);
 		break;
+	case 't': /* report text area size in characters */
+		if (param_count == 1 && csiparam[0] == 18) {
+			char reply[32];
+			snprintf(reply, sizeof reply, "\e[8;%d;%dt", t->buffer->rows, t->buffer->cols);
+			vt_write(t, reply, strlen(reply));
+		}
+		break;
 	case 'c': /* primary device attributes, answer as a VT100 with advanced video */
 		if (t->ebuf[1] != '>' && t->ebuf[1] != '=' && (param_count == 0 || csiparam[0] == 0))
 			vt_write(t, "[?1;2c", 7);