diff --git a/pyfstat/core.py b/pyfstat/core.py
index aceda60351219f7560392e62f35193337516a508..a4784bf8043430d345a35f2ae10ad7e9dfd3a8c1 100755
--- a/pyfstat/core.py
+++ b/pyfstat/core.py
@@ -440,7 +440,11 @@ class ComputeFstat(object):
             self.FstatResults.multiFatoms[0], self.windowRange, False)
 
         if self.BSGL is False:
-            return 2*FS.F_mn.data[0][0]
+            twoF = 2*FS.F_mn.data[0][0]
+            if np.isnan(twoF):
+                return 0
+            else:
+                return twoF
 
         FstatResults_single = copy.copy(self.FstatResults)
         FstatResults_single.lenth = 1