diff --git a/apiclient/discovery.py b/apiclient/discovery.py
index a3d4beb..ca26025 100644
--- a/apiclient/discovery.py
+++ b/apiclient/discovery.py
@@ -52,6 +52,7 @@
 from http import MediaUpload
 from http import MediaFileUpload
 from model import JsonModel
+from model import RawModel
 
 URITEMPLATE = re.compile('{[^}]*}')
 VARNAME = re.compile('[a-zA-Z0-9_-]+')
@@ -437,8 +438,13 @@
       if self._developerKey:
         actual_query_params['key'] = self._developerKey
 
+      model = self._model
+      # If there is no schema for the response then presume a binary blob.
+      if 'response' not in methodDesc:
+        model = RawModel()
+
       headers = {}
-      headers, params, query, body = self._model.request(headers,
+      headers, params, query, body = model.request(headers,
           actual_path_params, actual_query_params, body_value)
 
       expanded_url = uritemplate.expand(pathUrl, params)
@@ -541,7 +547,7 @@
 
       logging.info('URL being requested: %s' % url)
       return self._requestBuilder(self._http,
-                                  self._model.response,
+                                  model.response,
                                   url,
                                   method=httpMethod,
                                   body=body,
diff --git a/apiclient/model.py b/apiclient/model.py
index b8271f9..7f40efa 100644
--- a/apiclient/model.py
+++ b/apiclient/model.py
@@ -161,7 +161,8 @@
     Returns:
       The query parameters properly encoded into an HTTP URI query string.
     """
-    params.update({'alt': self.alt_param})
+    if self.alt_param is not None:
+      params.update({'alt': self.alt_param})
     astuples = []
     for key, value in params.iteritems():
       if type(value) == type([]):
@@ -269,6 +270,25 @@
     return {}
 
 
+class RawModel(JsonModel):
+  """Model class for requests that don't return JSON.
+
+  Serializes and de-serializes between JSON and the Python
+  object representation of HTTP request, and returns the raw bytes
+  of the response body.
+  """
+  accept = '*/*'
+  content_type = 'application/json'
+  alt_param = None
+
+  def deserialize(self, content):
+    return content
+
+  @property
+  def no_content_response(self):
+    return ''
+
+
 class ProtocolBufferModel(BaseModel):
   """Model class for protocol buffers.