diff --git a/utils.py b/utils.py
index 9c8cb077a2193ea0cdf56021594defddfb600fb7..104c4ca861d66ed5ca5eda468676c4e05fb37b38 100755
--- a/utils.py
+++ b/utils.py
@@ -435,6 +435,7 @@ def detection2time_freq(annotations_folder, duration, outdir, rf, names, wav, ra
 
     df['pos'] = (df['x'] * duration) + df['offset'].astype(int)
     df['Low Freq (Hz)'] = (1 - df['y']) * (rf / 2) - (df['h'] * (rf / 2)) / 2
+    df.loc[df['Low Freq (Hz)'] < 0, 'Low Freq (Hz)'] = 0
     df['High Freq (Hz)'] = (1 - df['y']) * (rf / 2) + (df['h'] * (rf / 2)) / 2
     df['Begin Time (s)'] = df['pos'] - (df['w'] * duration) / 2
     df['End Time (s)'] = df['pos'] + (df['w'] * duration) / 2