diff --git a/src/validators/hostname.py b/src/validators/hostname.py
index bdf6bdb..1c4f603 100644
--- a/src/validators/hostname.py
+++ b/src/validators/hostname.py
@@ -114,6 +114,8 @@ def hostname(
         return False
 
     if may_have_port and (host_seg := _port_validator(value)):
+        if len(host_seg) > 253:
+            return False
         return (
             (_simple_hostname_regex().match(host_seg) if maybe_simple else False)
             or domain(host_seg, consider_tld=consider_tld, rfc_1034=rfc_1034, rfc_2782=rfc_2782)
@@ -121,6 +123,9 @@ def hostname(
             or (False if skip_ipv6_addr else ipv6(host_seg, cidr=False))
         )
 
+    if len(value) > 253:
+        return False
+
     return (
         (_simple_hostname_regex().match(value) if maybe_simple else False)
         or domain(value, consider_tld=consider_tld, rfc_1034=rfc_1034, rfc_2782=rfc_2782)
diff --git a/tests/test_hostname.py b/tests/test_hostname.py
index 6ff4040..fde616c 100644
--- a/tests/test_hostname.py
+++ b/tests/test_hostname.py
@@ -40,6 +40,16 @@ def test_returns_true_on_valid_hostname(value: str, rfc_1034: bool, rfc_2782: bo
 @pytest.mark.parametrize(
     ("value", "rfc_1034", "rfc_2782"),
     [
+        # bad (hostname exceeding 253 chars)
+        (
+            "kld8MXQh6YalMqKRbfs895gMjW5T4p2EwToPoCSThPHHbXgmXc."
+            "kld8MXQh6YalMqKRbfs895gMjW5T4p2EwToPoCSThPHHbXgmXc."
+            "kld8MXQh6YalMqKRbfs895gMjW5T4p2EwToPoCSThPHHbXgmXc."
+            "kld8MXQh6YalMqKRbfs895gMjW5T4p2EwToPoCSThPHHbXgmXc."
+            "kld8MXQh6YalMqKRbfs895gMjW5T4p2EwToPoCSThPHHbXgmXcab",
+            False,
+            False,
+        ),
         # bad (simple hostname w/ optional ports)
         ("ubuntu-pc:443080", False, False),
         ("this-pc-is-sh*t", False, False),