diff --git a/bfps/DNS.py b/bfps/DNS.py
index c407a955c3d7e9ffd50bd69850b3b64296c65aa1..28291be5a980c4661ec545edf7ddcb8d822a9c2f 100644
--- a/bfps/DNS.py
+++ b/bfps/DNS.py
@@ -718,7 +718,7 @@ class DNS(_code):
             opt.dkx = 2. / opt.Lx
         if type(opt.dky) == type(None):
             opt.dky = 2. / opt.Ly
-        if type(opt.dkx) == type(None):
+        if type(opt.dkz) == type(None):
             opt.dkz = 2. / opt.Lz
         if type(opt.nx) == type(None):
             opt.nx = opt.n
diff --git a/bfps/test/test_Parseval.py b/bfps/test/test_Parseval.py
index aa6804269dc25aca25c7fa70755decd5652bea85..b2afdbeed989b09e22bf8af21e5c1c5d6f4e288f 100644
--- a/bfps/test/test_Parseval.py
+++ b/bfps/test/test_Parseval.py
@@ -31,14 +31,17 @@ def main():
     energyk = c.statistics['energy(k)']
     nshell = c.get_data_file()['kspace/nshell'].value
     renergy = np.mean(c.statistics['renergy(t)'])
-    print(renergy, np.trapz(energyk[:-2], c.statistics['kshell'][:-2]))
+    print(renergy, np.sum(energyk[:-2]) * (c.parameters['dkx']*c.parameters['dky']*c.parameters['dkz']))
+    print(c.parameters['dkx'], c.parameters['dky'], c.parameters['dkz'])
 
     f = plt.figure()
     a = f.add_subplot(111)
-    a.plot(c.statistics['kshell'], energyk)
-    a.plot(c.statistics['kshell'], (energyk / nshell)*(4*np.pi*c.statistics['kshell']**2))
-    a.set_yscale('log')
+    a.plot(c.statistics['kshell'], energyk, label = 'unnormalized')
+    a.plot(c.statistics['kshell'], (energyk / nshell)*(4*np.pi*c.statistics['kshell']**2), label = 'normalized')
+    #a.set_yscale('log')
     a.set_xscale('log')
+    a.legend(loc = 'best')
+    f.tight_layout()
     f.savefig('spectrum.pdf')
     return None