diff --git a/projects/pzsdr1/common/pzsdr1_constr_lvds.xdc b/projects/pzsdr1/common/pzsdr1_constr_lvds.xdc
index c5e8e10c4..da996fea6 100644
--- a/projects/pzsdr1/common/pzsdr1_constr_lvds.xdc
+++ b/projects/pzsdr1/common/pzsdr1_constr_lvds.xdc
@@ -37,6 +37,6 @@ set_property  -dict {PACKAGE_PIN  G20  IOSTANDARD LVDS_25}  [get_ports tx_data_o
 
 # clocks
 
-create_clock -name rx_clk       -period  4 [get_ports rx_clk_in_p]
-create_clock -name ad9361_clk   -period  4 [get_pins i_system_wrapper/system_i/axi_ad9361/clk]
+create_clock -name rx_clk       -period  8 [get_ports rx_clk_in_p]
+create_clock -name ad9361_clk   -period  8 [get_pins i_system_wrapper/system_i/axi_ad9361/clk]