diff --git a/2-test-generation/good-outputs/.gitkeep b/2-test-generation/good-outputs/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/2-test-generation/readme.md b/2-test-generation/readme.md
index dc727f3..f28c88b 100644
--- a/2-test-generation/readme.md
+++ b/2-test-generation/readme.md
@@ -30,4 +30,6 @@ Go back to the `2-test-generation` folder, type the following command:
 ```bash
 ./heterogen-fuzz good-seeds/ good-outputs/ 1000 ../test-program/a.out
 ```
+Make sure output folder exists before using heterogen-fuzz.
+
 You can find the generated test inputs in `good-outputs` folder. The generated inputs will be used to check behavior preservation in the automated code edit process. This step generates the results presented in Table 4. Please note that fuzzing is a random test generation process; thus, the results vary significantly across different runs.