diff --git a/lib/SDRAM/ddr_sdr_v1_5/src/sdram_types.vhd b/lib/SDRAM/ddr_sdr_v1_5/src/sdram_types.vhd
index fdc09be..5520b28 100644
--- a/lib/SDRAM/ddr_sdr_v1_5/src/sdram_types.vhd
+++ b/lib/SDRAM/ddr_sdr_v1_5/src/sdram_types.vhd
@@ -24,6 +24,7 @@
 library IEEE;
 USE IEEE.STD_LOGIC_1164.ALL;
 USE IEEE.NUMERIC_STD.ALL;
+USE IEEE.MATH_REAL.ALL;
 
 use work.sdram_config.all;
 
@@ -122,7 +123,7 @@ package body sdram_types is
 	function to_cycles(T_ns : real; f_Mhz : real) return natural is
 	begin
 		
-		return natural(0.5 + 1.0E-3*T_ns*f_Mhz);
+		return natural(ceil(1.0E-3*T_ns*f_Mhz));
 
 	end to_cycles;	
 
diff --git a/lib/misc/async_types.vhd b/lib/misc/async_types.vhd
index 2be444c..1509dc1 100644
--- a/lib/misc/async_types.vhd
+++ b/lib/misc/async_types.vhd
@@ -24,6 +24,7 @@
 library IEEE;
 USE IEEE.STD_LOGIC_1164.ALL;
 USE IEEE.NUMERIC_STD.ALL;
+USE IEEE.MATH_REAL.ALL;
 
 package async_types is
 
@@ -53,7 +54,7 @@ package body async_types is
 	function to_cycles(T_ns : real; f_Mhz : real) return natural is
 	begin
 		
-		return natural(0.5 + 1.0E-3*T_ns*f_Mhz);
+		return natural(ceil(1.0E-3*T_ns*f_Mhz));
 
 	end to_cycles;	
 end async_types;