diff --git a/src/TensorFlowNET.Core/c_api.cs b/src/TensorFlowNET.Core/APIs/c_api.cs
similarity index 100%
rename from src/TensorFlowNET.Core/c_api.cs
rename to src/TensorFlowNET.Core/APIs/c_api.cs
diff --git a/src/TensorFlowNET.Core/Tensors/tf.constant.cs b/src/TensorFlowNET.Core/APIs/tf.constant.cs
similarity index 53%
rename from src/TensorFlowNET.Core/Tensors/tf.constant.cs
rename to src/TensorFlowNET.Core/APIs/tf.constant.cs
index d60fb50e..3b44c13d 100644
--- a/src/TensorFlowNET.Core/Tensors/tf.constant.cs
+++ b/src/TensorFlowNET.Core/APIs/tf.constant.cs
@@ -9,7 +9,12 @@ namespace Tensorflow
     {
         public static Tensor constant(NDArray nd, string name = "Const", bool verify_shape = false)
         {
-            return constant_op.Create(nd, name, verify_shape);
+            //constant_op.Create(nd, name, verify_shape);
+            var graph = tf.get_default_graph();
+            var tensor = new Tensor(nd);
+            var op = graph.NewOperation("Const", name, tensor);
+            
+            return null;
         }
     }
 }
diff --git a/src/TensorFlowNET.Core/Graphs/Graph.Operation.cs b/src/TensorFlowNET.Core/Graphs/Graph.Operation.cs
new file mode 100644
index 00000000..8cd202e4
--- /dev/null
+++ b/src/TensorFlowNET.Core/Graphs/Graph.Operation.cs
@@ -0,0 +1,38 @@
+using NumSharp.Core;
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace Tensorflow
+{
+    public partial class Graph
+    {
+        public Operation NewOperation(string opType, string opName, Tensor tensor)
+        {
+            var desc = c_api.TF_NewOperation(_handle, opType, opName);
+
+            if (tensor.dtype == TF_DataType.TF_STRING)
+            {
+                var value = "Hello World!";
+                var bytes = Encoding.UTF8.GetBytes(value);
+                var buf = Marshal.AllocHGlobal(bytes.Length + 1);
+                Marshal.Copy(bytes, 0, buf, bytes.Length);
+                c_api.TF_SetAttrString(desc, "value", buf, (uint)value.Length);
+            }
+            else
+            {
+                c_api.TF_SetAttrTensor(desc, "value", tensor, Status);
+            }
+            
+            Status.Check();
+
+            c_api.TF_SetAttrType(desc, "dtype", tensor.dtype);
+
+            var op = c_api.TF_FinishOperation(desc, Status);
+            Status.Check();
+
+            return op;
+        }
+    }
+}
diff --git a/src/TensorFlowNET.Core/Graphs/Graph.cs b/src/TensorFlowNET.Core/Graphs/Graph.cs
index a20fe727..8f50f37b 100644
--- a/src/TensorFlowNET.Core/Graphs/Graph.cs
+++ b/src/TensorFlowNET.Core/Graphs/Graph.cs
@@ -41,21 +41,6 @@ namespace Tensorflow
             _names_in_use = new Dictionary<string, int>();
         }
 
-        public Operation NewOperation(string opType, string opName, Tensor t)
-        {
-            var desc = c_api.TF_NewOperation(_handle, opType, opName);
-            
-            c_api.TF_SetAttrTensor(desc, "value", t, Status);
-            Status.Check();
-
-            c_api.TF_SetAttrType(desc, "dtype", t.dtype);
-
-            var op = c_api.TF_FinishOperation(desc, Status);
-            Status.Check();
-
-            return op;
-        }
-
         public T as_graph_element<T>(T obj, bool allow_tensor = true, bool allow_operation = true)
         {
             return _as_graph_element_locked(obj, allow_tensor, allow_operation);
diff --git a/src/TensorFlowNET.Core/Tensors/Tensor.cs b/src/TensorFlowNET.Core/Tensors/Tensor.cs
index c321af8a..3fa6ca5d 100644
--- a/src/TensorFlowNET.Core/Tensors/Tensor.cs
+++ b/src/TensorFlowNET.Core/Tensors/Tensor.cs
@@ -83,8 +83,14 @@ namespace Tensorflow
                     Marshal.Copy(nd.Data<double>(), 0, dotHandle, nd.size);
                     break;
                 case "String":
-                    dotHandle = Marshal.StringToHGlobalAuto(nd.Data<string>()[0]);
-                    size = (ulong)nd.Data<string>()[0].Length;
+                    var value = nd.Data<string>()[0];
+                    var bytes = Encoding.UTF8.GetBytes(value);
+                    var buf = Marshal.AllocHGlobal(bytes.Length + 1);
+                    Marshal.Copy(bytes, 0, buf, bytes.Length);
+
+                    //c_api.TF_SetAttrString(op, "value", buf, (uint)bytes.Length);
+
+                    size = (ulong)bytes.Length;
                     break;
                 default:
                     throw new NotImplementedException("Marshal.Copy failed.");