diff --git a/testcases/step9/arg_swap.c b/testcases/step9/arg_swap.c
new file mode 100644
index 0000000..399c795
--- /dev/null
+++ b/testcases/step9/arg_swap.c
@@ -0,0 +1,11 @@
+int g(int a, int b) {
+    return a + b;
+}
+
+int f(int x, int y) {
+    return g(y, x);
+}
+
+int main() {
+    return f(2, 3);
+}
\ No newline at end of file