diff --git a/prosit/layers.py b/prosit/layers.py
index 9e642f9..608f2d3 100644
--- a/prosit/layers.py
+++ b/prosit/layers.py
@@ -32,7 +32,7 @@ def __init__(
     def build(self, input_shape):
         assert len(input_shape) == 3
         self.W = self.add_weight(
-            (input_shape[-1],),
+            shape=(input_shape[-1],),
             initializer=self.init,
             name="{}_W".format(self.name),
             regularizer=self.W_regularizer,
@@ -40,7 +40,7 @@ def build(self, input_shape):
         )
         if self.bias:
             self.b = self.add_weight(
-                (input_shape[1],),
+                shape=(input_shape[1],),
                 initializer="zero",
                 name="{}_b".format(self.name),
                 regularizer=self.b_regularizer,
@@ -50,7 +50,7 @@ def build(self, input_shape):
             self.b = None
         if self.context:
             self.u = self.add_weight(
-                (input_shape[-1],),
+                shape=(input_shape[-1],),
                 initializer=self.init,
                 name="{}_u".format(self.name),
                 regularizer=self.u_regularizer,