diff --git a/src/TensorFlowNET.Keras/Activations/Activations.Sigmoid.cs b/src/TensorFlowNET.Keras/Activations/Activations.Sigmoid.cs
index 67a7fa98..84220f4f 100644
--- a/src/TensorFlowNET.Keras/Activations/Activations.Sigmoid.cs
+++ b/src/TensorFlowNET.Keras/Activations/Activations.Sigmoid.cs
@@ -17,7 +17,9 @@ namespace Tensorflow.Keras
                 return results[0];
             }
 
-            throw new NotImplementedException("");
+            var _op = tf.OpDefLib._apply_op_helper("Sigmoid", name: name, args: new { x = features });
+
+            return _op.output;
         };
     }
 }
diff --git a/src/TensorFlowNET.Keras/Activations/Activations.Tanh.cs b/src/TensorFlowNET.Keras/Activations/Activations.Tanh.cs
index fb74c539..30bbdbf4 100644
--- a/src/TensorFlowNET.Keras/Activations/Activations.Tanh.cs
+++ b/src/TensorFlowNET.Keras/Activations/Activations.Tanh.cs
@@ -17,7 +17,9 @@ namespace Tensorflow.Keras
                 return results[0];
             }
 
-            throw new NotImplementedException("");
+            var _op = tf.OpDefLib._apply_op_helper("Tanh", name: name, args: new { x = features });
+
+            return _op.output;
         };
     }
 }