diff --git a/test_audioinput.py b/test_audioinput.py
index 779ef3a..213e1a4 100644
--- a/test_audioinput.py
+++ b/test_audioinput.py
@@ -2,11 +2,13 @@
 
 """
 test_audioinput.py
-Quick sanity check to ensure audio input device is working.
-Records 2 seconds of audio from default input and plots waveform.
+Records 2 seconds of audio from the default input device
+and saves the waveform as 'waveform.png' — works headless.
 """
 
 import numpy as np
+import matplotlib
+matplotlib.use('Agg')  # Headless backend
 import matplotlib.pyplot as plt
 import sounddevice as sd
 
@@ -21,7 +23,7 @@ sd.wait()
 # Generate time axis
 time_axis = np.linspace(0, DURATION, len(recording))
 
-# Plot
+# Plot and save
 plt.figure(figsize=(10, 4))
 plt.plot(time_axis, recording, linewidth=0.5)
 plt.title("Audio Input Waveform")
@@ -29,4 +31,6 @@ plt.xlabel("Time [s]")
 plt.ylabel("Amplitude")
 plt.grid(True)
 plt.tight_layout()
-plt.show()
+plt.savefig("waveform.png")
+
+print("✅ Waveform saved as 'waveform.png'")