diff --git a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Program.vb b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Program.vb
index 7938edbe47f755addd83bb7a12cbbfdec2895134..6e727d92247646020f6cf8865e65c62c898d1c45 100644
--- a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Program.vb
+++ b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Program.vb
@@ -4,6 +4,7 @@ Imports System.IO
 Imports System.Collections.Generic
 Imports System.Console
 Imports System.Runtime.InteropServices
+Imports System.Security.Cryptography
 
 ''' <summary>
 ''' Contains the startup code, command line argument processing, and driving the execution of the tool.
@@ -19,7 +20,7 @@ Friend Module Program
             Dim outputKind As String = Nothing
             Dim paths As New List(Of String)()
 
-            For Each arg in args
+            For Each arg In args
                 Dim c = arg.ToLowerInvariant()
                 If c = "/test" OrElse c = "/source" OrElse c = "/gettext" Then
                     If outputKind IsNot Nothing Then
@@ -27,7 +28,7 @@ Friend Module Program
                         Return exitWithErrors
                     End If
                     outputKind = c
-                Else If c = "/?" Then
+                ElseIf c = "/?" Then
                     PrintUsage()
                     Return exitWithErrors
                 Else
@@ -54,7 +55,8 @@ Friend Module Program
                 Return exitWithErrors
             End If
 
-            WriteOutput(outputFile, definition, outputKind)
+            Dim checksum = GetChecksum(inputFile)
+            WriteOutput(outputFile, definition, outputKind, checksum)
 
             Return exitWithoutErrors
 
@@ -67,6 +69,14 @@ Friend Module Program
 
     End Function
 
+    Private Function GetChecksum(filePath As String) As String
+        Dim fileBytes = File.ReadAllBytes(filePath)
+        Dim func = SHA256.Create()
+        Dim hashBytes = func.ComputeHash(fileBytes)
+        Dim data = BitConverter.ToString(hashBytes)
+        Return data.Replace("-", "")
+    End Function
+
     Private Sub PrintUsage()
         WriteLine("VBSyntaxGenerator.exe input output [/source] [/test]")
         WriteLine("  /source        Generates syntax model source code.")
@@ -84,11 +94,11 @@ Friend Module Program
         Return True
     End Function
 
-    Public Sub WriteOutput(outputFile As String, definition As ParseTree, outputKind As String)
+    Public Sub WriteOutput(outputFile As String, definition As ParseTree, outputKind As String, checksum As String)
 
         Using output As New StreamWriter(outputFile)
             output.WriteLine("' Definition of syntax model.")
-            output.WriteLine("' Generated by a tool on {0:g}", Date.Now)
+            output.WriteLine("' Generated by a tool from SHA256 content {0}", checksum)
             output.WriteLine("' DO NOT HAND EDIT")
 
 
@@ -102,7 +112,7 @@ Friend Module Program
                     output.WriteLine("Imports Roslyn.Utilities")
                     output.WriteLine("Imports Xunit")
 
-                    Dim testWriter As New TestWriter(definition)
+                    Dim testWriter As New TestWriter(definition, checksum)
                     testWriter.WriteTestCode(output)
 
                 Case "/gettext"
diff --git a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Tests/TestWriter.vb b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Tests/TestWriter.vb
index 0c32658cb93215c178462dcce8cc524690a62341..576411a2fb841b4eb5b5bc0f84256445840b40e4 100644
--- a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Tests/TestWriter.vb
+++ b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Tests/TestWriter.vb
@@ -11,12 +11,14 @@ Imports System.IO
 Public Class TestWriter
     Inherits WriteUtils
 
+    Private ReadOnly _checksum As String
     Private _writer As TextWriter    'output is sent here.
     Private Const s_externalSourceDirectiveString As String = "ExternalSourceDirective"
 
     ' Initialize the class with the parse tree to write.
-    Public Sub New(parseTree As ParseTree)
+    Public Sub New(parseTree As ParseTree, checksum As String)
         MyBase.New(parseTree)
+        _checksum = checksum
     End Sub
 
     ' Write out the code defining the tree to the give file.
@@ -28,7 +30,7 @@ Public Class TestWriter
 
     Private Sub GenerateFile()
         _writer.WriteLine("' Tests for parse trees.")
-        _writer.WriteLine("' Generated by a tool on {0:g}", DateTime.Now)
+        _writer.WriteLine("' Generated by a tool from SHA256 content {0}", _checksum)
         _writer.WriteLine("' DO NOT HAND EDIT")
         _writer.WriteLine()
 
diff --git a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Util/WriteDumper.vb b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Util/WriteDumper.vb
index c2246c6a94f744c7ddd3aa4c859f056597c7f107..20c7ec6df19368cc5924442e2d57fd1da57d60ae 100644
--- a/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Util/WriteDumper.vb
+++ b/src/Tools/Source/CompilerGeneratorTools/Source/VisualBasicSyntaxGenerator/Util/WriteDumper.vb
@@ -11,10 +11,12 @@ Imports System.IO
 Friend Class WriteDumper
     Inherits WriteUtils
 
+    Private ReadOnly _checksum As String
     Private _writer As TextWriter    'output is sent here.
 
-    Public Sub New(parseTree As ParseTree)
+    Public Sub New(parseTree As ParseTree, checksum As String)
         MyBase.New(parseTree)
+        _checksum = checksum
     End Sub
 
     ' Write the dumper utility function to the given file.
@@ -29,7 +31,7 @@ Friend Class WriteDumper
     ' Write the whole contents of the file.
     Private Sub GenerateFile()
         _writer.WriteLine("' Definition of parse trees dumper.")
-        _writer.WriteLine("' Generated by a tool on {0:g}", DateTime.Now)
+        _writer.WriteLine("' Generated by a tool from SHA256 content {0}", _checksum)
         _writer.WriteLine("' DO NOT HAND EDIT")
         _writer.WriteLine()