diff --git a/drivers/clk/aspeed/clk_ast2500.c b/drivers/clk/aspeed/clk_ast2500.c
index af369cc..26a5e58 100644
--- a/drivers/clk/aspeed/clk_ast2500.c
+++ b/drivers/clk/aspeed/clk_ast2500.c
@@ -35,7 +35,7 @@
 	const ulong post_div = (mpll_reg >> SCU_MPLL_POST_SHIFT)
 			& SCU_MPLL_POST_MASK;
 
-	return (clkin * ((num + 1) / (denum + 1))) / post_div;
+	return (clkin * ((num + 1) / (denum + 1))) / (post_div + 1);
 }
 
 /*
@@ -50,7 +50,7 @@
 	const ulong post_div = (hpll_reg >> SCU_HPLL_POST_SHIFT)
 			& SCU_HPLL_POST_MASK;
 
-	return (clkin * ((num + 1) / (denum + 1))) / post_div;
+	return (clkin * ((num + 1) / (denum + 1))) / (post_div + 1);
 }
 
 static ulong ast2500_get_clkin(struct ast2500_scu *scu)