diff --git a/include/h.h b/include/h.h
index 525147704..d01876d4a 100644
--- a/include/h.h
+++ b/include/h.h
@@ -820,6 +820,7 @@ extern MODVAR int (*do_remote_nick_name)(char *nick);
 extern MODVAR const char *(*charsys_get_current_languages)(void);
 extern MODVAR void (*broadcast_sinfo)(Client *acptr, Client *to, Client *except);
 extern MODVAR void (*connect_server)(ConfigItem_link *aconf, Client *by, struct hostent *hp);
+extern MODVAR int (*is_services_but_not_ulined)(Client *client);
 extern MODVAR void (*parse_message_tags)(Client *cptr, char **str, MessageTag **mtag_list);
 extern MODVAR const char *(*mtags_to_string)(MessageTag *m, Client *acptr);
 extern MODVAR int (*can_send_to_channel)(Client *cptr, Channel *channel, const char **msgtext, const char **errmsg, int notice);
diff --git a/include/modules.h b/include/modules.h
index 8f3924b6a..10fd11fda 100644
--- a/include/modules.h
+++ b/include/modules.h
@@ -2507,6 +2507,7 @@ enum EfunctionType {
 	EFUNC_CHARSYS_GET_CURRENT_LANGUAGES,
 	EFUNC_BROADCAST_SINFO,
 	EFUNC_CONNECT_SERVER,
+	EFUNC_IS_SERVICES_BUT_NOT_ULINED,
 	EFUNC_PARSE_MESSAGE_TAGS,
 	EFUNC_MTAGS_TO_STRING,
 	EFUNC_TKL_CHARTOTYPE,
diff --git a/src/api-efunctions.c b/src/api-efunctions.c
index 601eb62b9..aa7962847 100644
--- a/src/api-efunctions.c
+++ b/src/api-efunctions.c
@@ -106,6 +106,7 @@ int (*do_remote_nick_name)(char *nick);
 const char *(*charsys_get_current_languages)(void);
 void (*broadcast_sinfo)(Client *client, Client *to, Client *except);
 void (*connect_server)(ConfigItem_link *aconf, Client *by, struct hostent *hp);
+int (*is_services_but_not_ulined)(Client *client);
 void (*parse_message_tags)(Client *client, char **str, MessageTag **mtag_list);
 const char *(*mtags_to_string)(MessageTag *m, Client *client);
 int (*can_send_to_channel)(Client *client, Channel *channel, const char **msgtext, const char **errmsg, int notice);
@@ -389,6 +390,7 @@ void efunctions_init(void)
 	efunc_init_function(EFUNC_CHARSYS_GET_CURRENT_LANGUAGES, charsys_get_current_languages, NULL);
 	efunc_init_function(EFUNC_BROADCAST_SINFO, broadcast_sinfo, NULL);
 	efunc_init_function(EFUNC_CONNECT_SERVER, connect_server, NULL);
+	efunc_init_function(EFUNC_IS_SERVICES_BUT_NOT_ULINED, is_services_but_not_ulined, NULL);
 	efunc_init_function(EFUNC_PARSE_MESSAGE_TAGS, parse_message_tags, &parse_message_tags_default_handler);
 	efunc_init_function(EFUNC_MTAGS_TO_STRING, mtags_to_string, &mtags_to_string_default_handler);
 	efunc_init_function(EFUNC_TKL_CHARTOTYPE, tkl_chartotype, NULL);
diff --git a/src/modules/protoctl.c b/src/modules/protoctl.c
index c45af25e0..b4d48c4b8 100644
--- a/src/modules/protoctl.c
+++ b/src/modules/protoctl.c
@@ -277,6 +277,11 @@ CMD_FUNC(cmd_protoctl)
 				client->server->features.protocol = atoi(protocol);
 			if (software)
 				safe_strdup(client->server->features.software, software);
+			if (is_services_but_not_ulined(client))
+			{
+				exit_client_fmt(client, NULL, "Services detected but no ulines { } for server name %s", client->name);
+				return;
+			}
 			if (!IsHandshake(client) && aconf) /* Send PASS early... */
 				sendto_one(client, NULL, "PASS :%s", (aconf->auth->type == AUTHTYPE_PLAINTEXT) ? aconf->auth->data : "*");
 		}
diff --git a/src/modules/server.c b/src/modules/server.c
index 995311015..a40a589b3 100644
--- a/src/modules/server.c
+++ b/src/modules/server.c
@@ -57,6 +57,7 @@ void server_generic_free(ModData *m);
 int server_post_connect(Client *client);
 void _connect_server(ConfigItem_link *aconf, Client *by, struct hostent *hp);
 static int connect_server_helper(ConfigItem_link *, Client *);
+int _is_services_but_not_ulined(Client *client);
 
 /* Global variables */
 static cfgstruct cfg;
@@ -81,6 +82,7 @@ MOD_TEST()
 	EfunctionAdd(modinfo->handle, EFUNC_CHECK_DENY_VERSION, _check_deny_version);
 	EfunctionAddVoid(modinfo->handle, EFUNC_BROADCAST_SINFO, _broadcast_sinfo);
 	EfunctionAddVoid(modinfo->handle, EFUNC_CONNECT_SERVER, _connect_server);
+	EfunctionAdd(modinfo->handle, EFUNC_IS_SERVICES_BUT_NOT_ULINED, _is_services_but_not_ulined);
 	HookAdd(modinfo->handle, HOOKTYPE_CONFIGTEST, 0, server_config_test);
 	return MOD_SUCCESS;
 }
@@ -1979,3 +1981,25 @@ static int connect_server_helper(ConfigItem_link *aconf, Client *client)
 	return 1;
 }
 
+int _is_services_but_not_ulined(Client *client)
+{
+	if (!client->server || !client->server->features.software || !*client->name)
+		return 0; /* cannot detect software version or name not available yet */
+
+	if (our_strcasestr(client->server->features.software, "anope") ||
+	    our_strcasestr(client->server->features.software, "atheme"))
+	{
+		if (!find_uline(client->name))
+		{
+			unreal_log(ULOG_ERROR, "link", "LINK_NO_ULINES", client,
+			           "Server $client is a services server ($software). "
+			           "However, server $me does not have $client in the ulines { } block, "
+			           "which is required for services servers. "
+			           "See https://www.unrealircd.org/docs/Ulines_block",
+			           log_data_client("me", &me),
+			           log_data_string("software", client->server->features.software));
+			return 1; /* Is services AND no ulines { } entry */
+		}
+	}
+	return 0;
+}
diff --git a/src/modules/sinfo.c b/src/modules/sinfo.c
index 451db5854..15235a2f5 100644
--- a/src/modules/sinfo.c
+++ b/src/modules/sinfo.c
@@ -104,6 +104,14 @@ CMD_FUNC(sinfo_server)
 	else
 		safe_strdup(client->server->features.software, parv[parc-1]);
 
+	if (is_services_but_not_ulined(client))
+	{
+		char buf[512];
+		snprintf(buf, sizeof(buf), "Services detected but no ulines { } for server name %s", client->name);
+		exit_client_ex(client, &me, NULL, buf);
+		return;
+	}
+
 	/* Broadcast to 'the other side' of the net */
 	concat_params(buf, sizeof(buf), parc, parv);
 	sendto_server(client, 0, 0, NULL, ":%s SINFO %s", client->id, buf);