diff --git a/lasp/tools/tools.py b/lasp/tools/tools.py
index ef720f8..fdf69a8 100644
--- a/lasp/tools/tools.py
+++ b/lasp/tools/tools.py
@@ -136,6 +136,7 @@ def smoothSpectralData(freq, M, sw: SmoothingWidth,
     x0 = 1 if freq[0] == 0 else 0  # Skip first data point if zero frequency
     Psm[0] = P[0]                  # Reuse old value in case first data..
                                    # ..point is skipped. Not plotted any way.
+    P[-1] = P[-2]                  # Last data point (Nyquist f) often invalid
 
     # Loop through data points
     for x in range(x0, L):
@@ -173,7 +174,7 @@ def smoothSpectralData(freq, M, sw: SmoothingWidth,
 
         # Apply smoothing
         Psm[x] = np.dot(g, P[xl:xu])
-
+    
     if st == SmoothingType.levels:
         Psm = 10*np.log10(Psm)