diff --git a/day2/vhdl/run.sh b/day2/vhdl/run.sh
index 530ec7d..2094a93 100755
--- a/day2/vhdl/run.sh
+++ b/day2/vhdl/run.sh
@@ -3,20 +3,21 @@
 set -eu
 
 INPUT=$1
+MODE=${2:-}
 GHDLFLAGS="--std=08 --workdir=workdir"
 
 mkdir -p workdir
 
-ghdl remove $GHDLFLAGS
-ghdl analyze $GHDLFLAGS parser.vhd verifier.vhd top.vhd sim.vhd
-ghdl elab-run $GHDLFLAGS sim -gSTEP=1 < "$INPUT"
-ghdl elab-run $GHDLFLAGS sim -gSTEP=2 < "$INPUT"
-
-echo "Synthesized: "
-
-for step in 1 2; do
+if [[ $MODE = "--synth" ]]; then
+	for step in 1 2; do
+		ghdl remove $GHDLFLAGS
+		ghdl synth $GHDLFLAGS -gCOUNTER_WIDTH=12 -gSTEP="$step" parser.vhd verifier.vhd top.vhd -e top > top_syn.vhd 2>/dev/null
+		ghdl analyze $GHDLFLAGS top_syn.vhd sim.vhd
+		ghdl elab-run $GHDLFLAGS sim -gSTEP="$step" --ieee-asserts=disable < "$INPUT"
+	done
+else
 	ghdl remove $GHDLFLAGS
-	ghdl synth $GHDLFLAGS -gCOUNTER_WIDTH=12 -gSTEP="$step" parser.vhd verifier.vhd top.vhd -e top > top_syn.vhd
-	ghdl analyze $GHDLFLAGS top_syn.vhd sim.vhd
-	ghdl elab-run $GHDLFLAGS sim -gSTEP="$step" --ieee-asserts=disable < "$INPUT"
-done
+	ghdl analyze $GHDLFLAGS parser.vhd verifier.vhd top.vhd sim.vhd
+	ghdl elab-run $GHDLFLAGS sim -gSTEP=1 < "$INPUT"
+	ghdl elab-run $GHDLFLAGS sim -gSTEP=2 < "$INPUT"
+fi