diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index c3f434c51..2f3dfb012 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -282,7 +282,7 @@ struct SynthXilinxPass : public ScriptPass
 			}
 			else if (widemux > 0) {
 				run("simplemap t:$mux");
-				std::string muxcover_args = " -dmux=0";
+				std::string muxcover_args = " -nodecode";
 				switch (widemux) {
 					// NB: Cost of mux2 is 100; mux8 should cost between 3 and 4
 					//     of those so that 4:1 muxes and below are implemented