diff --git a/fishbook/reproclasses.py b/fishbook/reproclasses.py
index a763778..fcca08c 100644
--- a/fishbook/reproclasses.py
+++ b/fishbook/reproclasses.py
@@ -107,6 +107,7 @@ class BaselineData:
         for i in range(self.size):
             phases = self.__spike_phases(index=i)
             cstds.append(circstd(phases))
+        return cstds
 
     def eod_frequency(self):
         eodfs = []