diff --git a/src/i810_reg.h b/src/i810_reg.h
index 6458008c..e9c03e50 100644
--- a/src/i810_reg.h
+++ b/src/i810_reg.h
@@ -1577,7 +1577,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 # define TV_ENC_C0_FIX			(1 << 10)
 /** Bits that must be preserved by software */
-# define TV_CTL_SAVE			((3 << 8) | (3 << 6))
+# define TV_CTL_SAVE			((1 << 11) | (3 << 9) | (7 << 6) | 0xf)
 # define TV_FUSE_STATE_MASK		(3 << 4)
 /** Read-only state that reports all features enabled */
 # define TV_FUSE_STATE_ENABLED		(0 << 4)
diff --git a/src/i830_tv.c b/src/i830_tv.c
index 4063588b..d02bc114 100644
--- a/src/i830_tv.c
+++ b/src/i830_tv.c
@@ -1042,7 +1042,8 @@ i830_tv_mode_set(xf86OutputPtr output, DisplayModePtr mode,
     if (!tv_mode)
 	return;	/* can't happen (mode_prepare prevents this) */
 
-    tv_ctl = 0;
+    tv_ctl = INREG(TV_CTL);
+    tv_ctl &= TV_CTL_SAVE;
 
     switch (dev_priv->type) {
 	default: