diff --git a/src/spikeinterface/preprocessing/filter_gaussian.py b/src/spikeinterface/preprocessing/filter_gaussian.py
index 845082034e..e111007a06 100644
--- a/src/spikeinterface/preprocessing/filter_gaussian.py
+++ b/src/spikeinterface/preprocessing/filter_gaussian.py
@@ -104,7 +104,7 @@ def get_traces(
         else:
             neg_factor = np.zeros((traces.shape[0],))
 
-        filtered_fft = traces_fft * (pos_factor - neg_factor)[:, None]
+        filtered_fft = traces_fft * (pos_factor * (1 - neg_factor))[:, None]
         filtered_traces = np.real(np.fft.ifft(filtered_fft, axis=0))
 
         if np.issubdtype(dtype, np.integer):