diff --git a/source/train/DescrptSeA.py b/source/train/DescrptSeA.py
index 527dff2cce..dfe7329445 100644
--- a/source/train/DescrptSeA.py
+++ b/source/train/DescrptSeA.py
@@ -289,7 +289,10 @@ def _compute_dstats_sys_smth (self,
 
 
     def _compute_std (self,sumv2, sumv, sumn) :
-        return np.sqrt(sumv2/sumn - np.multiply(sumv/sumn, sumv/sumn))
+        val = np.sqrt(sumv2/sumn - np.multiply(sumv/sumn, sumv/sumn))
+        if np.abs(val) < 1e-2:
+            val = 1e-2
+        return val
 
 
     def _filter(self, 
diff --git a/source/train/DescrptSeR.py b/source/train/DescrptSeR.py
index aaa91ca220..f7f8147a6c 100644
--- a/source/train/DescrptSeR.py
+++ b/source/train/DescrptSeR.py
@@ -246,7 +246,11 @@ def _compute_dstats_sys_se_r (self,
 
 
     def _compute_std (self,sumv2, sumv, sumn) :
-        return np.sqrt(sumv2/sumn - np.multiply(sumv/sumn, sumv/sumn))
+        val = np.sqrt(sumv2/sumn - np.multiply(sumv/sumn, sumv/sumn))
+        if np.abs(val) < 1e-2:
+            val = 1e-2
+        return val
+
 
     def _filter_r(self, 
                   inputs,