diff --git a/mibuild/xilinx_ise.py b/mibuild/xilinx_ise.py
index d6ac472..8d82dae 100644
--- a/mibuild/xilinx_ise.py
+++ b/mibuild/xilinx_ise.py
@@ -84,6 +84,7 @@ def _build_files(device, sources, named_sc, named_pc, build_n
 -opt_mode SPEED
 -reduce_control_sets auto
 -register_balancing yes
+-fsm_encoding one-hot
 -ofn %s.ngc
 -p %s""" % (build_name, build_name, device)
        tools.write_to_file(build_name + ".xst", xst_contents)