diff --git a/drivers/video/sis/sis_main.c b/drivers/video/sis/sis_main.c
index 559bf1727a2b8f252a193d6fac276aed56124428..b52f8e4ef1fdbe3cd19c70d4fb282d15f5b99f85 100644
--- a/drivers/video/sis/sis_main.c
+++ b/drivers/video/sis/sis_main.c
@@ -1701,6 +1701,9 @@ static int	sisfb_ioctl(struct fb_info *info, unsigned int cmd,
 		break;
 
 	   case FBIOGET_VBLANK:
+
+		memset(&sisvbblank, 0, sizeof(struct fb_vblank));
+
 		sisvbblank.count = 0;
 		sisvbblank.flags = sisfb_setupvbblankflags(ivideo, &sisvbblank.vcount, &sisvbblank.hcount);