diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index 463c2063a..121bcff1f 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -102,8 +102,8 @@ struct SynthIce40Pass : public ScriptPass
 		log("\n");
 	}
 
-	string top_opt, blif_file, edif_file, json_file, abc, device_opt;
-	bool nocarry, nodffe, nobram, dsp, flatten, retime, noabc, abc2, vpr;
+	string top_opt, blif_file, edif_file, json_file, device_opt;
+	bool nocarry, nodffe, nobram, dsp, flatten, retime, noabc, abc2, vpr, abc9;
 	int min_ce_use;
 
 	void clear_flags() YS_OVERRIDE
@@ -122,7 +122,7 @@ struct SynthIce40Pass : public ScriptPass
 		noabc = false;
 		abc2 = false;
 		vpr = false;
-		abc = "abc";
+		abc9 = false;
 		device_opt = "hx";
 	}
 
@@ -207,7 +207,7 @@ struct SynthIce40Pass : public ScriptPass
 				continue;
 			}
 			if (args[argidx] == "-abc9") {
-				abc = "abc9";
+				abc9 = true;
 				continue;
 			}
 			if (args[argidx] == "-device" && argidx+1 < args.size()) {
@@ -223,7 +223,7 @@ struct SynthIce40Pass : public ScriptPass
 		if (device_opt != "hx" && device_opt != "lp" && device_opt !="u")
 			log_cmd_error("Invalid or no device specified: '%s'\n", device_opt.c_str());
 
-		if (abc == "abc9" && retime)
+		if (abc9 && retime)
 			log_cmd_error("-retime option not currently compatible with -abc9!\n");
 
 		log_header(design, "Executing SYNTH_ICE40 pass.\n");
@@ -316,7 +316,7 @@ struct SynthIce40Pass : public ScriptPass
 				run("techmap -map +/techmap.v -map +/ice40/arith_map.v");
 			}
 			if (retime || help_mode)
-				run(abc + " -dff -D 1", "(only if -retime)");
+				run("abc -dff -D 1", "(only if -retime)");
 			run("ice40_opt");
 		}
 
@@ -340,7 +340,7 @@ struct SynthIce40Pass : public ScriptPass
 		if (check_label("map_luts"))
 		{
 			if (abc2 || help_mode) {
-				run(abc, "      (only if -abc2)");
+				run("abc", "      (only if -abc2)");
 				run("ice40_opt", "(only if -abc2)");
 			}
 			run("techmap -map +/ice40/latches_map.v");
@@ -349,7 +349,7 @@ struct SynthIce40Pass : public ScriptPass
 				run("techmap -map +/gate2lut.v -D LUT_WIDTH=4", "(only if -noabc)");
 			}
 			if (!noabc) {
-				if (abc == "abc9") {
+				if (abc9) {
 					run("read_verilog -icells -lib +/ice40/abc9_model.v");
 					int wire_delay;
 					if (device_opt == "lp")
@@ -358,10 +358,10 @@ struct SynthIce40Pass : public ScriptPass
 						wire_delay = 750;
 					else
 						wire_delay = 250;
-					run(abc + stringf(" -W %d -lut +/ice40/abc9_%s.lut -box +/ice40/abc9_%s.box", wire_delay, device_opt.c_str(), device_opt.c_str()), "(skip if -noabc)");
+					run(stringf("abc9 -W %d -lut +/ice40/abc9_%s.lut -box +/ice40/abc9_%s.box", wire_delay, device_opt.c_str(), device_opt.c_str()));
 				}
 				else
-					run(abc + " -dress -lut 4", "(skip if -noabc)");
+					run("abc -dress -lut 4", "(skip if -noabc)");
 			}
 			run("ice40_wrapcarry -unwrap");
 			run("techmap -D NO_LUT -map +/ice40/cells_map.v");