diff --git a/src/runtime/pythonengine.cs b/src/runtime/pythonengine.cs
index 700543839..5073067d3 100644
--- a/src/runtime/pythonengine.cs
+++ b/src/runtime/pythonengine.cs
@@ -503,7 +503,7 @@ public static PyObject ReloadModule(PyObject module)
         /// </remarks>
         public static PyObject ModuleFromString(string name, string code)
         {
-            IntPtr c = Runtime.Py_CompileString(code, "none", (IntPtr)257);
+            IntPtr c = Runtime.Py_CompileString(code, "none", (int)RunFlagType.File);
             Runtime.CheckExceptionOccurred();
             IntPtr m = Runtime.PyImport_ExecCodeModule(name, c);
             Runtime.CheckExceptionOccurred();
@@ -512,7 +512,7 @@ public static PyObject ModuleFromString(string name, string code)
 
         public static PyObject Compile(string code, string filename = "", RunFlagType mode = RunFlagType.File)
         {
-            var flag = (IntPtr)mode;
+            var flag = (int)mode;
             IntPtr ptr = Runtime.Py_CompileString(code, filename, flag);
             Runtime.CheckExceptionOccurred();
             return new PyObject(ptr);
@@ -610,7 +610,7 @@ internal static PyObject RunString(string code, IntPtr? globals, IntPtr? locals,
         }
     }
 
-    public enum RunFlagType
+    public enum RunFlagType : int
     {
         Single = 256,
         File = 257, /* Py_file_input */
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
index 7a78cd6e1..66f5ed123 100644
--- a/src/runtime/runtime.cs
+++ b/src/runtime/runtime.cs
@@ -763,8 +763,36 @@ public static extern int Py_Main(
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
         internal static extern IntPtr PyEval_EvalCode(IntPtr co, IntPtr globals, IntPtr locals);
 
+#if PYTHON2
+        [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
+        internal static extern IntPtr Py_CompileString(string code, string file, int start);
+#else
+        /// <summary>
+        /// Return value: New reference.
+        /// This is a simplified interface to Py_CompileStringFlags() below, leaving flags set to NULL.
+        /// </summary>
+        internal static IntPtr Py_CompileString(string str, string file, int start)
+        {
+            return Py_CompileStringFlags(str, file, start, IntPtr.Zero);
+        }
+
+        /// <summary>
+        /// Return value: New reference.
+        /// This is a simplified interface to Py_CompileStringExFlags() below, with optimize set to -1.
+        /// </summary>
+        internal static IntPtr Py_CompileStringFlags(string str, string file, int start, IntPtr flags)
+        {
+            return Py_CompileStringExFlags(str, file, start, flags, -1);
+        }
+
+        /// <summary>
+        /// Return value: New reference.
+        /// Like Py_CompileStringObject(), but filename is a byte string decoded from the filesystem encoding(os.fsdecode()).
+        /// </summary>
+        /// <returns></returns>
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
-        internal static extern IntPtr Py_CompileString(string code, string file, IntPtr tok);
+        internal static extern IntPtr Py_CompileStringExFlags(string str, string file, int start, IntPtr flags, int optimize);
+#endif
 
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
         internal static extern IntPtr PyImport_ExecCodeModule(string name, IntPtr code);