diff --git a/docs/journeys.md b/docs/journeys.md
index 016f052c..b566edb3 100644
--- a/docs/journeys.md
+++ b/docs/journeys.md
@@ -40,7 +40,10 @@ With `opt`, you can override the default options, which look like this:
 
 ```js
 {
-	when: new Date(),
+	// Use either `departure` or `arrival` to specify a date/time.
+	departure: new Date(),
+	arrival: null,
+
 	earlierThan: null, // ref to get journeys earlier than the last query
 	laterThan: null, // ref to get journeys later than the last query
 	results: 5, // how many journeys?
diff --git a/index.js b/index.js
index 69f831ea..cb3f312f 100644
--- a/index.js
+++ b/index.js
@@ -69,8 +69,8 @@ const createClient = (profile, request = _request) => {
 			if (!isNonEmptyString(opt.earlierThan)) {
 				throw new Error('opt.earlierThan must be a non-empty string.')
 			}
-			if ('when' in opt) {
-				throw new Error('opt.earlierThan and opt.when are mutually exclusive.')
+			if (('departure' in opt) || ('arrival' in opt)) {
+				throw new Error('opt.earlierThan and opt.departure/opt.arrival are mutually exclusive.')
 			}
 			journeysRef = opt.earlierThan
 		}
@@ -78,8 +78,8 @@ const createClient = (profile, request = _request) => {
 			if (!isNonEmptyString(opt.laterThan)) {
 				throw new Error('opt.laterThan must be a non-empty string.')
 			}
-			if ('when' in opt) {
-				throw new Error('opt.laterThan and opt.when are mutually exclusive.')
+			if (('departure' in opt) || ('arrival' in opt)) {
+				throw new Error('opt.laterThan and opt.departure/opt.arrival are mutually exclusive.')
 			}
 			journeysRef = opt.laterThan
 		}
@@ -97,8 +97,19 @@ const createClient = (profile, request = _request) => {
 			polylines: false // return leg shapes?
 		}, opt)
 		if (opt.via) opt.via = profile.formatLocation(profile, opt.via, 'opt.via')
-		opt.when = new Date(opt.when || Date.now())
-		if (Number.isNaN(+opt.when)) throw new Error('opt.when is invalid')
+
+		if (opt.when !== undefined) {
+			throw new Error('opt.when is not supported anymore. Use opt.departure/opt.arrival.')
+		}
+		let when = new Date(), outFrwd = true
+		if (opt.departure !== undefined && opt.departure !== null) {
+			when = new Date(opt.departure)
+			if (Number.isNaN(+when)) throw new Error('opt.departure is invalid')
+		} else if (opt.arrival !== undefined && opt.arrival !== null) {
+			when = new Date(opt.arrival)
+			if (Number.isNaN(+when)) throw new Error('opt.arrival is invalid')
+			outFrwd = false
+		}
 
 		const filters = [
 			profile.formatProductsFilter(opt.products || {})
@@ -132,10 +143,10 @@ const createClient = (profile, request = _request) => {
 				arrLocL: [to],
 				jnyFltrL: filters,
 				getTariff: !!opt.tickets,
+				outFrwd,
 
 				// todo: what is req.gisFltrL?
 				getPT: true, // todo: what is this?
-				outFrwd: true, // todo: what is this?
 				getIV: false, // todo: walk & bike as alternatives?
 				getPolyline: !!opt.polylines
 			}
@@ -172,7 +183,7 @@ const createClient = (profile, request = _request) => {
 			})
 		}
 
-		return more(opt.when, journeysRef)
+		return more(when, journeysRef)
 	}
 
 	const locations = (query, opt = {}) => {