diff --git a/projects/fmcadc2/vc707/system_constr.xdc b/projects/fmcadc2/vc707/system_constr.xdc
index 866c24a69..2de57cd6f 100644
--- a/projects/fmcadc2/vc707/system_constr.xdc
+++ b/projects/fmcadc2/vc707/system_constr.xdc
@@ -41,6 +41,7 @@ create_clock -name rx_ref_clk   -period  1.60 [get_ports rx_ref_clk_p]
 create_clock -name rx_div_clk   -period  6.40 [get_pins i_system_wrapper/system_i/util_fmcadc2_xcvr/inst/i_xch_0/i_gtxe2_channel/RXOUTCLK]
 
 set_false_path -from [get_cells i_system_wrapper/system_i/axi_ad9625_jesd_rstgen/U0/PR_OUT_DFF[0].peripheral_reset_reg[0]]
+set_property IOB false [get_cells -hierarchical -filter {name =~ *SCK_O_NE_4_FDRE_INST}]
 
 set_property ASYNC_REG TRUE [get_cells -hier -filter {name =~ *sysref_en_m*}]
 set_false_path -to [get_cells -hier -filter {name =~ *sysref_en_m1*  && IS_SEQUENTIAL}]