diff --git a/build.sh b/build.sh
index 878c28c..7301bc4 100644
--- a/build.sh
+++ b/build.sh
@@ -1,9 +1,22 @@
 #!/usr/bin/env sh
 
+set -xe
+
 CFLAGS="-Wall -Wextra -std=c11 -ggdb -fsanitize=address -fsanitize=undefined"
 SRC="vec.c symtable.c tag.c constructor.c sys.c main.c"
 OUT="alisp.out"
 
-set -xe
+build() {
+    cc $CFLAGS -o $OUT $SRC;
+}
 
-cc $CFLAGS -o $OUT $SRC;
+run() {
+    ./$OUT;
+}
+
+build
+
+if [ "$1" = "run" ]
+then
+    run
+fi