diff --git a/ChangeLog b/ChangeLog
index fe7f01af4..f77b74067 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2008-07-01  Chris Lord  <chris@openedhand.com>
+
+	* clutter/clutter-stage.c:
+	Add a note to the clutter_stage_read_pixels doc that the alpha channel
+	isn't guaranteed to contain sensible data
+
+	* tests/test-stage-read-pixels.c: (update_snapshot):
+	Overwrite the alpha data when using clutter_stage_read_pixels; fixes
+	this test on non-nvidia drivers
+
 2008-07-01  Matthew Allum  <mallum@openedhand.com>
 
 	* clutter/glx/clutter-stage-glx.c:
diff --git a/clutter/clutter-stage.c b/clutter/clutter-stage.c
index ce0f6ce15..f6535bb4d 100644
--- a/clutter/clutter-stage.c
+++ b/clutter/clutter-stage.c
@@ -1122,6 +1122,9 @@ clutter_stage_hide_cursor (ClutterStage *stage)
  * Makes a screenshot of the stage in RGBA 8bit data, returns a
  * linear buffer with @width * 4 as rowstride.
  *
+ * The alpha data contained in the returned buffer is driver-dependent, 
+ * and not guaranteed to hold any sensible value.
+ *
  * Return value: a pointer to newly allocated memory with the buffer
  *   or %NULL if the read failed. Use g_free() on the returned data
  *   to release the resources it has allocated.
diff --git a/tests/test-stage-read-pixels.c b/tests/test-stage-read-pixels.c
index 70e263874..e063ab3cb 100644
--- a/tests/test-stage-read-pixels.c
+++ b/tests/test-stage-read-pixels.c
@@ -89,11 +89,20 @@ static gboolean update_snapshot (gpointer data)
   SuperOH *oh = data;
   gint    width = CLUTTER_STAGE_WIDTH();
   gint    height = CLUTTER_STAGE_HEIGHT();
+  gint    x, y, rowstride;
   guchar *pixels;
 
   pixels = clutter_stage_read_pixels (CLUTTER_STAGE (oh->stage), 0, 0, width, height);
   g_assert (pixels);
 
+  /* Alpha data is not guaranteed to be sensible and we don't need it, 
+   * overwrite it with full-alpha.
+   */
+  rowstride = width * 4;
+  for (y = 0; y < height; y++)
+    for (x = 3; x < rowstride; x += 4)
+      pixels[(y * rowstride) + x] = 0xff;
+  
   clutter_texture_set_from_rgb_data (CLUTTER_TEXTURE (oh->tv), pixels, TRUE, width, height, width *4,
    4, 0, NULL);
   g_free (pixels);