diff --git a/keras_contrib/layers/advanced_activations.py b/keras_contrib/layers/advanced_activations.py
index 22b896a..345fb14 100644
--- a/keras_contrib/layers/advanced_activations.py
+++ b/keras_contrib/layers/advanced_activations.py
@@ -66,6 +66,7 @@ class PELU(Layer):
                 param_shape[i - 1] = 1
                 self.param_broadcast[i - 1] = True
 
+        param_shape = tuple(param_shape)
         # Initialised as ones to emulate the default ELU
         self.alpha = self.add_weight(param_shape,
                                      name='alpha',
@@ -175,6 +176,8 @@ class SReLU(Layer):
                 param_shape[i - 1] = 1
                 self.param_broadcast[i - 1] = True
 
+        param_shape = tuple(param_shape)
+
         self.t_left = self.add_weight(param_shape,
                                       name='t_left',
                                       initializer=self.t_left_initializer)