diff --git a/lib/client.js b/lib/client.js
index a34a6f861..80d489229 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -1704,11 +1704,6 @@ MatrixClient.prototype.paginateEventTimeline = function(eventTimeline, opts) {
         }
     }
 
-    var room = this.getRoom(eventTimeline.getRoomId());
-    if (!room) {
-        throw new Error("Unknown room " + eventTimeline.getRoomId());
-    }
-
     var dir = backwards ? EventTimeline.BACKWARDS : EventTimeline.FORWARDS;
 
     var token = eventTimeline.getPaginationToken(dir);
@@ -1766,6 +1761,11 @@ MatrixClient.prototype.paginateEventTimeline = function(eventTimeline, opts) {
         eventTimeline._paginationRequests[dir] = promise;
     }
     else {
+        var room = this.getRoom(eventTimeline.getRoomId());
+        if (!room) {
+            throw new Error("Unknown room " + eventTimeline.getRoomId());
+        }
+
         var path = utils.encodeUri(
             "/rooms/$roomId/messages", {$roomId: eventTimeline.getRoomId()}
         );