diff --git a/drivers/video/fbdev/tridentfb.c b/drivers/video/fbdev/tridentfb.c
index 4d20cb557ff0..319131bd72cf 100644
--- a/drivers/video/fbdev/tridentfb.c
+++ b/drivers/video/fbdev/tridentfb.c
@@ -996,6 +996,9 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var,
 	int ramdac = 230000; /* 230MHz for most 3D chips */
 	debug("enter\n");
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	/* check color depth */
 	if (bpp == 24)
 		bpp = var->bits_per_pixel = 32;