diff --git a/src/main.c b/src/main.c
index 9a61ddd..2ebd8b4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -125,7 +125,7 @@ static void copy_framebuffer() {
 #if DISP_WIDTH==640 && DISP_HEIGHT==480
     uint32_t *dest = umac_framebuffer_mirror;
     for(int i=0; i<640*480/32; i++) {
-        *dest++ = *src++;
+        *dest++ = *src++ ^ 0xffffffff;
     }
 #elif DISP_WIDTH==512 && DISP_HEIGHT==342
     #define DISP_XOFFSET ((640 - DISP_WIDTH) / 32 / 2)
diff --git a/src/video_hstx.c b/src/video_hstx.c
index b2379b5..91aa910 100644
--- a/src/video_hstx.c
+++ b/src/video_hstx.c
@@ -35,9 +35,9 @@
 // ----------------------------------------------------------------------------
 // DVI constants
 
-#define TMDS_CTRL_00 0x154u
+#define TMDS_CTRL_00 0x354u
 #define TMDS_CTRL_01 0x0abu
-#define TMDS_CTRL_10 0x354u
+#define TMDS_CTRL_10 0x154u
 #define TMDS_CTRL_11 0x2abu
 
 #define SYNC_V0_H0 (TMDS_CTRL_00 | (TMDS_CTRL_00 << 10) | (TMDS_CTRL_00 << 20))