diff --git a/keras_contrib/losses/dssim.py b/keras_contrib/losses/dssim.py
index 038f03f..735d722 100644
--- a/keras_contrib/losses/dssim.py
+++ b/keras_contrib/losses/dssim.py
@@ -53,7 +53,7 @@ class DSSIMObjective():
         var_true = K.var(patches_true, axis=-1)
         var_pred = K.var(patches_pred, axis=-1)
         # Get std dev
-        covar_true_pred = K.mean(patches_true*patches_pred, axis=-1) - u_true*u_pred
+        covar_true_pred = K.mean(patches_true * patches_pred, axis=-1) - u_true * u_pred
 
         ssim = (2 * u_true * u_pred + self.c1) * (2 * covar_true_pred + self.c2)
         denom = (K.square(u_true) + K.square(u_pred) + self.c1) * (var_pred + var_true + self.c2)