diff --git a/pywafo/src/wafo/spectrum/core.py b/pywafo/src/wafo/spectrum/core.py
index f32bfd6..8cc67cd 100644
--- a/pywafo/src/wafo/spectrum/core.py
+++ b/pywafo/src/wafo/spectrum/core.py
@@ -156,7 +156,8 @@ def qtf(w, h=inf, g=9.81):
 
     return h_s, h_d , h_dii
 
-#def plotspec(specdata, linetype='b-', flag=1):
+def plotspec(specdata, linetype='b-', flag=1):
+    pass
 #    '''
 #    PLOTSPEC Plot a spectral density 
 #    
@@ -2381,7 +2382,7 @@ class SpecData1D(PlotData):
         #m0 = self.moment(nr=0)
         m0 = simps(S, w)
         sa = sqrt(m0)
-        Nw = w.size
+        #Nw = w.size
 
         Hs, Hd, Hdii = qtf(w, h, g)
 
diff --git a/pywafo/src/wafo/spectrum/models.py b/pywafo/src/wafo/spectrum/models.py
index 2e5e846..adba09a 100644
--- a/pywafo/src/wafo/spectrum/models.py
+++ b/pywafo/src/wafo/spectrum/models.py
@@ -52,7 +52,7 @@ from numpy import (inf, atleast_1d, newaxis, any, minimum, maximum, array, #@Unr
     asarray, exp, log, sqrt, where, pi, arange, linspace, sin, cos, abs, sinh, #@UnresolvedImport
     isfinite, mod, expm1, tanh, cosh, finfo, ones, ones_like, isnan, #@UnresolvedImport
     zeros_like, flatnonzero, sinc, hstack, vstack, real, flipud, clip) #@UnresolvedImport
-from dispersion_relation import w2k, k2w #@UnusedImport
+from wafo.wave_theory.dispersion_relation import w2k, k2w #@UnusedImport
 from wafo.spectrum import SpecData1D, SpecData2D
 sech = lambda x: 1.0 / cosh(x)