diff --git a/src/i810_reg.h b/src/i810_reg.h
index 2893bc8..023282f 100644
--- a/src/i810_reg.h
+++ b/src/i810_reg.h
@@ -2146,7 +2146,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define I830_GMCH_MEM_64M	0x1
 #define I830_GMCH_MEM_128M	0
 
-#define I830_GMCH_GMS_MASK			0xF0
+#define I830_GMCH_GMS_MASK			0x70
 #define I830_GMCH_GMS_DISABLED			0x00
 #define I830_GMCH_GMS_LOCAL			0x10
 #define I830_GMCH_GMS_STOLEN_512		0x20