diff --git a/hw/kdrive/ati/ati_draw.c b/hw/kdrive/ati/ati_draw.c
index ead133b58..a47dc8973 100644
--- a/hw/kdrive/ati/ati_draw.c
+++ b/hw/kdrive/ati/ati_draw.c
@@ -214,8 +214,9 @@ RadeonSwitchTo3D(ATIScreenInfo *atis)
 	ENTER_DRAW(0);
 	BEGIN_DMA(4);
 	OUT_REG(RADEON_REG_RB3D_DSTCACHE_CTLSTAT, RADEON_RB3D_DC_FLUSH);
+	/* We must wait for 3d to idle, in case source was just written as a dest. */
 	OUT_REG(ATI_REG_WAIT_UNTIL,
-	    RADEON_WAIT_HOST_IDLECLEAN | RADEON_WAIT_2D_IDLECLEAN);
+	    RADEON_WAIT_HOST_IDLECLEAN | RADEON_WAIT_2D_IDLECLEAN | RADEON_WAIT_3D_IDLECLEAN);
 	END_DMA();
 	LEAVE_DRAW(0);
 }
diff --git a/hw/kdrive/ati/ati_reg.h b/hw/kdrive/ati/ati_reg.h
index 2b38bbee2..17b5db360 100644
--- a/hw/kdrive/ati/ati_reg.h
+++ b/hw/kdrive/ati/ati_reg.h
@@ -416,6 +416,10 @@
 # define RADEON_WAIT_BOTH_CRTC_PFLIP		(1 << 30)
 # define RADEON_ENG_DISPLAY_SELECT		(1 << 31)
 
+#define RADEON_REG_ISYNC_CNTL			0x1724
+#define ISYNC_ANY2D_IDLE3D			0x1
+#define ISYNC_ANY3D_IDLE2D			0x2
+
 #define R128_REG_GUI_STAT			0x1740
 # define R128_GUI_ACTIVE			(1 << 31)