diff --git a/lasp/tools/tools.py b/lasp/tools/tools.py
index 752ed7b..ef720f8 100644
--- a/lasp/tools/tools.py
+++ b/lasp/tools/tools.py
@@ -161,8 +161,8 @@ def smoothSpectralData(freq, M, sw: SmoothingWidth,
             fu = fNq  # no data beyond fNq
             fl = fc**2 / fu  # keep window symmetric
 
-        xl = bisect.bisect_left(f, fl)  # index corresponding to fl
-        xu = bisect.bisect_left(f, fu)
+        xl = bisect.bisect_left(freq, fl)  # index corresponding to fl
+        xu = bisect.bisect_left(freq, fu)
 
         # Calculate window
         g = np.zeros(xu-xl)
@@ -307,7 +307,7 @@ if __name__ == "__main__":
     fmin = 3e3   # [Hz] min freq
     fmax = 24e3  # [Hz] max freq
     Ndata = 200  # number of data points
-    f = np.linspace(fmin, fmax, Ndata)  # frequency points
+    freq = np.linspace(fmin, fmax, Ndata)  # frequency points
     M = abs(0.4*np.random.normal(size=(Ndata,)))+0.01  #
     M = 20*np.log10(M)
 
@@ -315,7 +315,7 @@ if __name__ == "__main__":
 #    fmin = 3e3   # [Hz] min freq
 #    fmax = 24e3  # [Hz] max freq
 #    Ndata = 200  # number of data points
-#    f = np.linspace(fmin, fmax, Ndata)  # frequency points
+#    freq = np.linspace(fmin, fmax, Ndata)  # frequency points
 #    M = 0 * abs(1+0.4*np.random.normal(size=(Ndata,))) + 0.01  #
 #    M[int(100)] = 1
 #    M = 20*np.log10(M)
@@ -325,12 +325,12 @@ if __name__ == "__main__":
         value = [Noct]
     st = SmoothingType.levels  # so data is given in dB
 
-    Msm = smoothSpectralData(f, M, sw, st)
-    fsm = f
+    Msm = smoothSpectralData(freq, M, sw, st)
+    fsm = freq
 
     # Plot - lin frequency
     plt.figure()
-    plt.plot(f, M, '.b')
+    plt.plot(freq, M, '.b')
     plt.plot(fsm, Msm,  'r')
     plt.xlabel('f (Hz)')
     plt.ylabel('magnitude')
@@ -339,7 +339,7 @@ if __name__ == "__main__":
 
     # Plot - log frequency
     plt.figure()
-    plt.semilogx(f, M, '.b')
+    plt.semilogx(freq, M, '.b')
     plt.semilogx(fsm, Msm,  'r')
     plt.xlabel('f (Hz)')
     plt.ylabel('magnitude')