diff --git a/lib/misc/gpio_wb.vhd b/lib/misc/gpio_wb.vhd
index 6df62c0..20cdfa0 100644
--- a/lib/misc/gpio_wb.vhd
+++ b/lib/misc/gpio_wb.vhd
@@ -3,6 +3,10 @@ USE IEEE.STD_LOGIC_1164.ALL;
 USE IEEE.NUMERIC_STD.ALL;
 
 ENTITY gpio_wb IS
+	Generic
+	(
+		f_sysclk_hz		: natural := 100E6
+	);
 	Port
 	(
 		CLK_I		: in  STD_LOGIC;
@@ -30,13 +34,14 @@ END gpio_wb;
 ARCHITECTURE behavior OF gpio_wb IS
 
 	constant num_timers	: natural := 2;
+	constant ncycles_usec	: natural := f_sysclk_hz/1E6;
 	
 	signal gpo0_reg		: unsigned(31 downto 0);
 	signal gpo1_reg		: unsigned(31 downto 0);
 	signal gpi0_reg		: unsigned(31 downto 0);
 	signal gpi1_reg		: unsigned(31 downto 0);
 	-- Signals to form an timer generating an interrupt every microsecond
-	subtype tick_usec_t	is natural range 0 to 99;
+	subtype tick_usec_t	is natural range 0 to ncycles_usec-1;
 	signal tick_usec		: tick_usec_t;
 	signal cnt_usec			: unsigned(31 downto 0);
 	signal cnt_sec			: unsigned(31 downto 0);