diff --git a/rtl/quartus/vortex.sdc b/rtl/quartus/vortex.sdc
index eafe4ff7..622e853d 100644
--- a/rtl/quartus/vortex.sdc
+++ b/rtl/quartus/vortex.sdc
@@ -1 +1,6 @@
+set_time_format -unit ns -decimal_places 3
+
 create_clock -name {clk} -period "400 MHz" -waveform { 0.0 1.0 } [get_ports {clk}]
+
+derive_pll_clocks -create_base_clocks
+derive_clock_uncertainty