Index: src/MTXClient.m
==================================================================
--- src/MTXClient.m
+++ src/MTXClient.m
@@ -201,11 +201,15 @@
 {
 	void *pool = objc_autoreleasePoolPush();
 	MTXRequest *request = [self
 	    requestWithPath: @"/_matrix/client/r0/sync"];
 	unsigned long long timeoutMs = timeout * 1000;
-	request.query = [OFString stringWithFormat: @"timeout=%llu", timeoutMs];
+	OFMutableDictionary<OFString *, OFString *> *query =
+	    [OFMutableDictionary dictionaryWithObject: @(timeoutMs).stringValue
+					       forKey: @"timeout"];
+	query[@"since"] = [_storage nextBatchForDeviceID: _deviceID];
+	request.query = query;
 	[request performWithBlock: ^ (mtx_response_t response, int statusCode,
 				       id exception) {
 		if (exception != nil) {
 			block(exception);
 			return;

Index: src/MTXRequest.h
==================================================================
--- src/MTXRequest.h
+++ src/MTXRequest.h
@@ -71,11 +71,12 @@
 @property (copy, nonatomic) OFString *path;
 
 /**
  * @brief The query for the request.
  */
-@property (copy, nullable, nonatomic) OFString *query;
+@property (copy, nullable, nonatomic)
+    OFDictionary<OFString *, OFString *> *query;
 
 /**
  * @brief An optional body to send along with the request.
  *
  * This is a dictionary that gets serialized to JSON when the request is sent.

Index: src/MTXRequest.m
==================================================================
--- src/MTXRequest.m
+++ src/MTXRequest.m
@@ -95,11 +95,11 @@
 		/* Not the best exception to indicate it's already in-flight. */
 		@throw [OFAlreadyConnectedException exception];
 
 	OFMutableURL *requestURL = [[_homeserver mutableCopy] autorelease];
 	requestURL.path = _path;
-	requestURL.query = _query;
+	requestURL.queryDictionary = _query;
 
 	OFMutableDictionary *headers = [OFMutableDictionary dictionary];
 	headers[@"User-Agent"] = @"ObjMatrix";
 	if (_accessToken != nil)
 		headers[@"Authorization"] =