diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index 07b6addbb3c1..243ea4ab20c8 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1339,10 +1339,8 @@ static int aty128_var_to_pll(u32 period_in_ps, struct aty128_pll *pll,
 	if (vclk * 12 < c.ppll_min)
 		vclk = c.ppll_min/12;
 
-	pll->post_divider = -1;
-
 	/* now, find an acceptable divider */
-	for (i = 0; i < sizeof(post_dividers); i++) {
+	for (i = 0; i < ARRAY_SIZE(post_dividers); i++) {
 		output_freq = post_dividers[i] * vclk;
 		if (output_freq >= c.ppll_min && output_freq <= c.ppll_max) {
 			pll->post_divider = post_dividers[i];
@@ -1350,7 +1348,7 @@ static int aty128_var_to_pll(u32 period_in_ps, struct aty128_pll *pll,
 		}
 	}
 
-	if (pll->post_divider < 0)
+	if (i == ARRAY_SIZE(post_dividers))
 		return -EINVAL;
 
 	/* calculate feedback divider */