diff --git a/ETA.py b/ETA.py
index e392b93..7741b15 100644
--- a/ETA.py
+++ b/ETA.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 import numpy as np
 import matplotlib.pyplot as plt
 import utils
diff --git a/spectrum.py b/spectrum.py
index febd78f..d90598b 100644
--- a/spectrum.py
+++ b/spectrum.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 import numpy as np
 import matplotlib.pyplot as plt
 from scipy.signal import medfilt , find_peaks