diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index 5a3b0a6353..9773a067d5 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -1005,7 +1005,7 @@ static int client_parse_message(
                         if (optlen != 4)
                                 return -EINVAL;
 
-                        irt = be32toh(*(be32_t *) optval) * USEC_PER_SEC;
+                        irt = unaligned_read_be32((be32_t *) optval) * USEC_PER_SEC;
                         break;
                 }
 
diff --git a/test/fuzz/fuzz-dhcp6-client/crash-13591 b/test/fuzz/fuzz-dhcp6-client/crash-13591
new file mode 100644
index 0000000000..20ac358f4d
Binary files /dev/null and b/test/fuzz/fuzz-dhcp6-client/crash-13591 differ