diff --git a/bfps/DNS.py b/bfps/DNS.py
index 3207cccea556fc5ee952ca196c39a462a7c5085e..9d57338d549e5710487c632f055cec44ea57ec7e 100644
--- a/bfps/DNS.py
+++ b/bfps/DNS.py
@@ -236,6 +236,9 @@ class DNS(_code):
             ii0 = iter0 // self.parameters['niter_stat']
             ii1 = iter1 // self.parameters['niter_stat']
             self.statistics['kshell'] = data_file['kspace/kshell'].value
+            for kk in [-1, -2]:
+                if (self.statistics['kshell'][kk] == 0):
+                    self.statistics['kshell'][kk] = np.nan
             self.statistics['kM'] = data_file['kspace/kM'].value
             self.statistics['dk'] = data_file['kspace/dk'].value
             computation_needed = True
diff --git a/bfps/NavierStokes.py b/bfps/NavierStokes.py
index 59fb907c4a79f73dec5b6a8cfcb06d99b0b584bb..b7bf4ff8322d1ed96f15023b0355bb79c0d482f1 100644
--- a/bfps/NavierStokes.py
+++ b/bfps/NavierStokes.py
@@ -598,6 +598,9 @@ class NavierStokes(_fluid_particle_base):
             ii0 = iter0 // self.parameters['niter_stat']
             ii1 = iter1 // self.parameters['niter_stat']
             self.statistics['kshell'] = data_file['kspace/kshell'].value
+            for kk in [-1, -2]:
+                if (self.statistics['kshell'][kk] == 0):
+                    self.statistics['kshell'][kk] = np.nan
             self.statistics['kM'] = data_file['kspace/kM'].value
             self.statistics['dk'] = data_file['kspace/dk'].value
             computation_needed = True