diff --git a/docs/server-info.md b/docs/server-info.md
index 681f311e..86db86f5 100644
--- a/docs/server-info.md
+++ b/docs/server-info.md
@@ -6,6 +6,7 @@ With `opt`, you can override the default options, which look like this:
 
 ```js
 {
+	versionInfo: true, // query HAFAS versions?
 	language: 'en', // depends on the profile
 }
 ```
@@ -25,6 +26,9 @@ console.log(await client.serverInfo())
 
 ```js
 {
+	// version of the HAFAS Connection Interface (HCI), the API that hafas-client uses
+	hciVersion: '1.23',
+
 	timetableStart: '20200517',
 	timetableEnd: '20201212',
 	serverTime: '2020-07-19T21:32:12+02:00',
diff --git a/index.js b/index.js
index 0b0ff1ae..075a7bb4 100644
--- a/index.js
+++ b/index.js
@@ -731,13 +731,22 @@ const createClient = (profile, userAgent, opt = {}) => {
 	}
 
 	const serverInfo = async (opt = {}) => {
+		opt = {
+			versionInfo: true, // query HAFAS versions?
+			...opt
+		}
+
 		const {res, common} = await profile.request({profile, opt}, userAgent, {
 			meth: 'ServerInfo',
-			req: {}
+			req: {
+				getVersionInfo: opt.versionInfo,
+			},
 		})
 
 		const ctx = {profile, opt, common, res}
 		return {
+			// todo: what are .serverVersion & .clientVersion?
+			hciVersion: res.hciVersion || null,
 			timetableStart: res.fpB || null,
 			timetableEnd: res.fpE || null,
 			serverTime: res.sD && res.sT
diff --git a/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45 b/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45
new file mode 100644
index 00000000..9818eed8
--- /dev/null
+++ b/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45
@@ -0,0 +1 @@
+{"ver":"1.34","ext":"DB.R20.12.b","lang":"eng","id":"ta2gikk4gaxhxkwg","err":"OK","cInfo":{"code":"OK","url":"","msg":""},"graph":{"id":"standard","index":0},"subGraph":{"id":"global","index":0},"view":{"id":"standard","index":0,"type":"WGS84"},"svcResL":[{"meth":"ServerInfo","err":"OK","res":{"fpB":"20211212","fpE":"20221210","sD":"20220222","sT":"202539","enc":"ISO-8859-1","planrtTS":"1645557831","serverVersion":"5.45.DB.R21.12.1.a (customer/hcudb/release/21.12.1.a.0) [Dec 17 2021]","clientVersion":"5.45.DB.R21.12.1.a (customer/hcudb/release/21.12.1.a.0) [Dec 17 2021]","hciVersion":"1.46"}}]}
\ No newline at end of file
diff --git a/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45.headers b/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45.headers
new file mode 100644
index 00000000..dbb6c87f
--- /dev/null
+++ b/test/e2e/fixtures/ec7d38b24537d986a55c1608474cda45.headers
@@ -0,0 +1,40 @@
+{
+  "statusCode": 200,
+  "headers": {
+    "date": "Tue, 22 Feb 2022 19:25:40 GMT",
+    "content-type": "application/json; charset=utf-8",
+    "content-length": "345",
+    "connection": "keep-alive",
+    "set-cookie": [
+      "AWSALB=ofa5BiXycld9XQJtZ8QTD823tDszyjr2sYpdBYbJCeWk4P+8+TUzu7oywsmVX9wivfMEDtEJyBipYc+SA33F2pYyStBnxkBIWvzo5mOIS+tGZWBlyN3csusXBpFd; Expires=Tue, 01 Mar 2022 19:25:39 GMT; Path=/",
+      "AWSALBCORS=ofa5BiXycld9XQJtZ8QTD823tDszyjr2sYpdBYbJCeWk4P+8+TUzu7oywsmVX9wivfMEDtEJyBipYc+SA33F2pYyStBnxkBIWvzo5mOIS+tGZWBlyN3csusXBpFd; Expires=Tue, 01 Mar 2022 19:25:39 GMT; Path=/; SameSite=None; Secure"
+    ],
+    "server": "Apache",
+    "strict-transport-security": "max-age=16070400; includeSubDomains"
+  },
+  "url": "https://reiseauskunft.bahn.de/bin/mgate.exe?checksum=ee1ddec720dddfcac82fb7f78649d72c",
+  "time": 304,
+  "request": {
+    "method": "POST",
+    "headers": {
+      "Content-Type": [
+        "application/json"
+      ],
+      "Accept-Encoding": [
+        "gzip, br, deflate"
+      ],
+      "Accept": [
+        "application/json"
+      ],
+      "user-agent": [
+        "public-1dd0bdtranspor1dd0bdt/haf1dd0bdas-clien1dd0bdt:test"
+      ],
+      "connection": [
+        "keep-alive"
+      ],
+      "Content-Length": [
+        "252"
+      ]
+    }
+  }
+}
\ No newline at end of file
diff --git a/test/e2e/lib/server-info.js b/test/e2e/lib/server-info.js
index 13a8b01c..6edf42bb 100644
--- a/test/e2e/lib/server-info.js
+++ b/test/e2e/lib/server-info.js
@@ -9,6 +9,9 @@ const testServerInfo = async (cfg) => {
 	const info = await fetchServerInfo()
 	t.ok(info, 'invalid info')
 
+	t.equal(typeof info.hciVersion, 'string', 'invalid info.hciVersion')
+	t.ok(info.hciVersion, 'invalid info.hciVersion')
+
 	t.equal(typeof info.timetableStart, 'string', 'invalid info.timetableStart')
 	t.ok(info.timetableStart, 'invalid info.timetableStart')
 	t.equal(typeof info.timetableEnd, 'string', 'invalid info.timetableEnd')