diff --git a/models.py b/models.py
index 717a5e8..006de43 100644
--- a/models.py
+++ b/models.py
@@ -47,6 +47,7 @@ def build( self, x ):
         super( MyNormLayer, self ).build(x)
         
     def call( self, x ):
+        eps = 1e-12
         x1, x2 = x
         bs, H, W, _ = [tf.shape(x1)[i] for i in range(4)]
         _, h, w, _ = [tf.shape(x2)[i] for i in range(4)]
@@ -55,8 +56,8 @@ def call( self, x ):
         concat = tf.concat([x1, x2], axis=1)
         x_mean = K.mean( concat, axis=1, keepdims=True )
         x_std = K.std( concat, axis=1, keepdims = True )
-        x1 = (x1 - x_mean) / x_std
-        x2 = (x2 - x_mean) / x_std
+        x1 = (x1 - x_mean) / (x_std + eps)
+        x2 = (x2 - x_mean) / (x_std + eps)
         x1 = tf.reshape(x1, ( bs, H, W, -1 ) )
         x2 = tf.reshape(x2, ( bs, h, w, -1 ) )
         return [x1, x2]
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