diff --git a/artiq/gateware/targets/kc705_dds.py b/artiq/gateware/targets/kc705_dds.py
index 47b1fb6f5..f990a39f6 100755
--- a/artiq/gateware/targets/kc705_dds.py
+++ b/artiq/gateware/targets/kc705_dds.py
@@ -112,7 +112,7 @@ _zotino = [
         Subsignal("clk", Pins("HPC:LA32_N")),
         Subsignal("ser", Pins("HPC:LA33_P")),
         Subsignal("latch", Pins("HPC:LA32_P")),
-        IOStandard("LVCMOS33")
+        IOStandard("LVCMOS25")
     ),
     ("zotino_spi_p", 0,
         Subsignal("clk", Pins("HPC:LA08_P")),