diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index 2e9176a84..bda03d251 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -268,9 +268,9 @@ struct SynthEcp5Pass : public ScriptPass
 			}
 			run("techmap -map +/ecp5/latches_map.v");
 			if (nomux)
-				run("abc -lut 4");
+				run("abc -lut 4 -dress");
 			else
-				run("abc -lut 4:7");
+				run("abc -lut 4:7 -dress");
 			run("clean");
 		}