diff --git a/matrix_client/api.py b/matrix_client/api.py
index 6c17f878..ee4e95fd 100644
--- a/matrix_client/api.py
+++ b/matrix_client/api.py
@@ -16,7 +16,8 @@
 import json
 import requests
 from time import time, sleep
-from .errors import MatrixError, MatrixRequestError, MatrixHttpLibError
+from .errors import MatrixError, MatrixRequestError, MatrixHttpLibError, \
+    MatrixTimeoutError
 
 try:
     from urllib import quote
@@ -50,6 +51,7 @@ def __init__(self, base_url, token=None, identity=None):
         self.identity = identity
         self.txn_id = 0
         self.validate_cert = True
+        self.default_timeout = 30
 
     def initial_sync(self, limit=1):
         """
@@ -645,6 +647,11 @@ def _send(self, method, path, content=None, query_params={}, headers={},
         if headers["Content-Type"] == "application/json" and content is not None:
             content = json.dumps(content)
 
+        if "timeout" in query_params:
+            request_timeout = 5 + query_params["timeout"] / 1000
+        else:
+            request_timeout = self.default_timeout
+
         response = None
         while True:
             try:
@@ -653,8 +660,13 @@ def _send(self, method, path, content=None, query_params={}, headers={},
                     params=query_params,
                     data=content,
                     headers=headers,
-                    verify=self.validate_cert
+                    verify=self.validate_cert,
+                    timeout=request_timeout
                 )
+
+            except requests.exceptions.Timeout as e:
+                raise MatrixTimeoutError(e, method, endpoint)
+
             except requests.exceptions.RequestException as e:
                 raise MatrixHttpLibError(e, method, endpoint)
 
diff --git a/matrix_client/client.py b/matrix_client/client.py
index 3ea1dc03..3ab0c977 100644
--- a/matrix_client/client.py
+++ b/matrix_client/client.py
@@ -410,7 +410,7 @@ def listen_forever(self, timeout_ms=30000, exception_handler=None):
                function which can be used to handle exceptions in the caller
                thread.
         """
-        bad_sync_timeout = 5000
+        bad_sync_timeout = 5
         self.should_listen = True
         while (self.should_listen):
             try:
diff --git a/matrix_client/errors.py b/matrix_client/errors.py
index ea604304..ee88812a 100644
--- a/matrix_client/errors.py
+++ b/matrix_client/errors.py
@@ -4,7 +4,7 @@ class MatrixError(Exception):
 
 
 class MatrixUnexpectedResponse(MatrixError):
-    """The home server gave an unexpected response. """
+    """The home server gave an unexpected response."""
 
     def __init__(self, content=""):
         super(MatrixError, self).__init__(content)
@@ -12,7 +12,7 @@ def __init__(self, content=""):
 
 
 class MatrixRequestError(MatrixError):
-    """ The home server returned an error response. """
+    """The home server returned an error response."""
 
     def __init__(self, code=0, content=""):
         super(MatrixRequestError, self).__init__("%d: %s" % (code, content))
@@ -30,3 +30,15 @@ def __init__(self, original_exception, method, endpoint):
                                                                   original_exception)
         )
         self.original_exception = original_exception
+
+
+class MatrixTimeoutError(MatrixHttpLibError):
+    """Client-side timeout in a request."""
+
+    def __init__(self, original_exception, method, endpoint):
+        super(MatrixHttpLibError, self).__init__(
+            "Timeout in {} requesting {}: {}".format(method,
+                                                     endpoint,
+                                                     original_exception)
+        )
+        self.original_exception = original_exception