diff --git a/picamera/camera.py b/picamera/camera.py
index 36b1202a..a7da1861 100644
--- a/picamera/camera.py
+++ b/picamera/camera.py
@@ -274,6 +274,7 @@ class PiCamera(object):
         'incandescent':  mmal.MMAL_PARAM_AWBMODE_INCANDESCENT,
         'flash':         mmal.MMAL_PARAM_AWBMODE_FLASH,
         'horizon':       mmal.MMAL_PARAM_AWBMODE_HORIZON,
+        'greyworld':     mmal.MMAL_PARAM_AWBMODE_GREYWORLD,
         }
 
     IMAGE_EFFECTS = {
diff --git a/picamera/mmal.py b/picamera/mmal.py
index 81b059fc..82b2b5fc 100644
--- a/picamera/mmal.py
+++ b/picamera/mmal.py
@@ -692,7 +692,8 @@ class MMAL_PARAMETER_EXPOSUREMETERINGMODE_T(ct.Structure):
     MMAL_PARAM_AWBMODE_INCANDESCENT,
     MMAL_PARAM_AWBMODE_FLASH,
     MMAL_PARAM_AWBMODE_HORIZON,
-) = range(10)
+    MMAL_PARAM_AWBMODE_GREYWORLD,
+) = range(11)
 MMAL_PARAM_AWBMODE_MAX = 0x7fffffff
 
 class MMAL_PARAMETER_AWBMODE_T(ct.Structure):