diff --git a/.gitpod.yml b/.gitpod.yml
new file mode 100644
index 0000000000..e35338e4a9
--- /dev/null
+++ b/.gitpod.yml
@@ -0,0 +1 @@
+image: mcr.microsoft.com/dotnet/sdk:5.0
\ No newline at end of file
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 37e6bfda47..6ccb5ba16f 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,3 +1,7 @@
+### 4.4.0-alpha-007 12/2020
+
+* Fix Program.fs inside full path can lead to invalid AST. [#1337](https://github.com/fsprojects/fantomas/issues/1337)
+
 ### 4.4.0-alpha-006 12/2020
 
 * Fix Formatting of long parameter lists. [#657](https://github.com/fsprojects/fantomas/issues/657)
diff --git a/src/Fantomas.CoreGlobalTool.Tests/Fantomas.CoreGlobalTool.Tests.fsproj b/src/Fantomas.CoreGlobalTool.Tests/Fantomas.CoreGlobalTool.Tests.fsproj
index 5f13cd36a9..3f8c989333 100644
--- a/src/Fantomas.CoreGlobalTool.Tests/Fantomas.CoreGlobalTool.Tests.fsproj
+++ b/src/Fantomas.CoreGlobalTool.Tests/Fantomas.CoreGlobalTool.Tests.fsproj
@@ -4,7 +4,7 @@
     <TargetFramework>net5.0</TargetFramework>
     <IsPackable>false</IsPackable>
     <GenerateProgramFile>false</GenerateProgramFile>
-    <Version>4.4.0-alpha-006</Version>
+    <Version>4.4.0-alpha-007</Version>
     <NoWarn>FS0988</NoWarn>
     <WarningsAsErrors>FS0025</WarningsAsErrors>
   </PropertyGroup>
diff --git a/src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj b/src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj
index 9c5233d9bd..6e93f60d76 100644
--- a/src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj
+++ b/src/Fantomas.CoreGlobalTool/Fantomas.CoreGlobalTool.fsproj
@@ -4,7 +4,7 @@
     <TargetFramework>net5.0</TargetFramework>
     <ToolCommandName>fantomas</ToolCommandName>
     <PackAsTool>True</PackAsTool>
-    <Version>4.4.0-alpha-006</Version>
+    <Version>4.4.0-alpha-007</Version>
     <AssemblyName>fantomas-tool</AssemblyName>
     <WarningsAsErrors>FS0025</WarningsAsErrors>
   </PropertyGroup>
diff --git a/src/Fantomas.Extras/Fantomas.Extras.fsproj b/src/Fantomas.Extras/Fantomas.Extras.fsproj
index 65f86d1b49..1adb3439f4 100644
--- a/src/Fantomas.Extras/Fantomas.Extras.fsproj
+++ b/src/Fantomas.Extras/Fantomas.Extras.fsproj
@@ -2,7 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <Version>4.4.0-alpha-006</Version>
+    <Version>4.4.0-alpha-007</Version>
     <Description>Utility package for Fantomas</Description>
     <WarningsAsErrors>FS0025</WarningsAsErrors>
   </PropertyGroup>
diff --git a/src/Fantomas.Tests/CodeFormatterTests.fs b/src/Fantomas.Tests/CodeFormatterTests.fs
index 3a893840e7..55a4939194 100644
--- a/src/Fantomas.Tests/CodeFormatterTests.fs
+++ b/src/Fantomas.Tests/CodeFormatterTests.fs
@@ -31,3 +31,30 @@ let main argv _ =
     )
     |> Async.RunSynchronously
     |> ignore
+
+[<Test>]
+let ``sanitize filename if path with Program.fs`` () =
+    let fileName = @"d:\dev\bootcamp\src\Program.fs"
+
+    let source = """
+open System
+open Poker.Main
+
+[<EntryPoint>]
+let main _ =
+    processInput Console.In Console.Out
+    0
+"""
+
+    let parsingOptions =
+        FakeHelpers.createParsingOptionsFromFile fileName
+
+    CodeFormatter.FormatDocumentAsync(
+        fileName,
+        SourceOrigin.SourceString source,
+        config,
+        parsingOptions,
+        sharedChecker.Value
+    )
+    |> Async.RunSynchronously
+    |> ignore
diff --git a/src/Fantomas.Tests/Fantomas.Tests.fsproj b/src/Fantomas.Tests/Fantomas.Tests.fsproj
index 371c73b17e..6d3ea00548 100644
--- a/src/Fantomas.Tests/Fantomas.Tests.fsproj
+++ b/src/Fantomas.Tests/Fantomas.Tests.fsproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <Version>4.4.0-alpha-006</Version>
+    <Version>4.4.0-alpha-007</Version>
     <NoWarn>FS0988</NoWarn>
     <TargetFramework>net5.0</TargetFramework>
     <WarningsAsErrors>FS0025</WarningsAsErrors>
diff --git a/src/Fantomas/CodeFormatterImpl.fs b/src/Fantomas/CodeFormatterImpl.fs
index 6caf30bf77..5a60726522 100644
--- a/src/Fantomas/CodeFormatterImpl.fs
+++ b/src/Fantomas/CodeFormatterImpl.fs
@@ -41,11 +41,14 @@ type FormatContext =
       SourceText: ISourceText }
 
 // Some file names have a special meaning for the F# compiler and the AST cannot be parsed.
-let safeFileName fileName =
+let safeFileName (file: string) =
+    let fileName =
+        file.Split([| '\\'; '/' |]) |> Array.last
+
     if fileName = "Program.fs" then
         "tmp.fsx"
     else
-        fileName
+        file
 
 let createFormatContext fileName (source: SourceOrigin) =
     let (sourceText, sourceCode) = getSourceTextAndCode source
diff --git a/src/Fantomas/Fantomas.fsproj b/src/Fantomas/Fantomas.fsproj
index fbfa1960fc..b3e4cf3a6f 100644
--- a/src/Fantomas/Fantomas.fsproj
+++ b/src/Fantomas/Fantomas.fsproj
@@ -2,7 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <Version>4.4.0-alpha-006</Version>
+    <Version>4.4.0-alpha-007</Version>
     <Description>Source code formatter for F#</Description>
     <WarningsAsErrors>FS0025</WarningsAsErrors>
   </PropertyGroup>