diff --git a/techlibs/fabulous/arith_map.v b/techlibs/fabulous/arith_map.v
deleted file mode 100644
index 8cf5a234b..000000000
--- a/techlibs/fabulous/arith_map.v
+++ /dev/null
@@ -1,64 +0,0 @@
-`default_nettype none
-
-`ifdef ARITH_ha
-(* techmap_celltype = "$alu" *)
-module _80_fabulous_ha_alu (A, B, CI, BI, X, Y, CO);
-
-parameter A_SIGNED = 0;
-parameter B_SIGNED = 0;
-parameter A_WIDTH = 1;
-parameter B_WIDTH = 1;
-parameter Y_WIDTH = 1;
-
-parameter _TECHMAP_CONSTMSK_CI_ = 0;
-parameter _TECHMAP_CONSTVAL_CI_ = 0;
-
-(* force_downto *)
-input [A_WIDTH-1:0] A;
-(* force_downto *)
-input [B_WIDTH-1:0] B;
-input CI, BI;
-(* force_downto *)
-output [Y_WIDTH-1:0] X, Y, CO;
-
-(* force_downto *)
-wire [Y_WIDTH-1:0] A_buf, B_buf;
-\$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
-\$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) B_conv (.A(B), .Y(B_buf));
-
-(* force_downto *)
-wire [Y_WIDTH-1:0] AA = A_buf;
-(* force_downto *)
-wire [Y_WIDTH-1:0] BB = BI ? ~B_buf : B_buf;
-wire [Y_WIDTH:0] CARRY;
-
-
-LUT4_HA #(
-	.INIT(16'b0),
-	.I0MUX(1'b1)
-) carry_statrt (
-	.I0(), .I1(CI), .I2(CI), .I3(),
-	.Ci(),
-	.Co(CARRY[0])
-);
-
-// Carry chain
-genvar i;
-generate for (i = 0; i < Y_WIDTH; i = i + 1) begin:slice
-	LUT4_HA #(
-		.INIT(16'b1001_0110_1001_0110), // full adder sum over (I2, I1, I0)
-		.I0MUX(1'b1)
-	) lut_i (
-		.I0(), .I1(AA[i]), .I2(BB[i]), .I3(),
-		.Ci(CARRY[i]),
-		.O(Y[i]),
-		.Co(CARRY[i+1])
-	);
-
-	assign CO[i] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
-end endgenerate
-
-assign X = AA ^ BB;
-
-endmodule
-`endif
diff --git a/techlibs/fabulous/synth_fabulous.cc b/techlibs/fabulous/synth_fabulous.cc
index 979db0165..e174da3ab 100644
--- a/techlibs/fabulous/synth_fabulous.cc
+++ b/techlibs/fabulous/synth_fabulous.cc
@@ -357,8 +357,7 @@ struct SynthPass : public ScriptPass
 
 		if (check_label("map_gates")) {
 			run("opt -full");
-			run(stringf("techmap -map +/techmap.v -map +/fabulous/arith_map.v -D ARITH_%s",
-				help_mode ? "<carry>" : carry_mode.c_str()));
+			run("techmap -map +/techmap.v");
 			run("opt -fast");
 		}
 
@@ -386,11 +385,12 @@ struct SynthPass : public ScriptPass
 
 		if (check_label("map_extra")) {
 			if (help_mode) {
-				run("techmap -map <extra_map.v>...", "(for each -extra-map)");
+				run("techmap -map <extra_map.v> -D ARITH_<carry>...", "(for each -extra-map)");
 			} else if (!extra_map.empty()) {
 				std::string map_str = "techmap";
 				for (auto map : extra_map)
 					map_str += stringf(" -map %s", map);
+				map_str += stringf(" -D ARITH_%s", carry_mode.c_str());
 				run(map_str);
 			}
 			run("simplemap");