diff --git a/passes/techmap/abc.cc b/passes/techmap/abc.cc
index 21b70f492..c828ad8ed 100644
--- a/passes/techmap/abc.cc
+++ b/passes/techmap/abc.cc
@@ -1674,6 +1674,8 @@ struct AbcPass : public Pass {
 			}
 			if (arg == "-dff") {
 				dff_mode = true;
+				if (delay_target.empty())
+					delay_target = "-D 0";
 				continue;
 			}
 			if (arg == "-clk" && argidx+1 < args.size()) {