diff --git a/UIX.RenderApi/UIX.RenderApi.csproj b/UIX.RenderApi/UIX.RenderApi.csproj
index 8483ed9..34427e5 100644
--- a/UIX.RenderApi/UIX.RenderApi.csproj
+++ b/UIX.RenderApi/UIX.RenderApi.csproj
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
-        <TargetFrameworks>net35;net6.0</TargetFrameworks>
+        <TargetFrameworks>net35;net40;net6.0</TargetFrameworks>
         <ProjectGuid>{CB2B7609-C7B8-4E2A-82D8-DD631B70B621}</ProjectGuid>
         <OutputType>Library</OutputType>
         <AssemblyName>UIX.RenderApi</AssemblyName>
diff --git a/UIX/UIX.csproj b/UIX/UIX.csproj
index 4f836d7..526ae07 100644
--- a/UIX/UIX.csproj
+++ b/UIX/UIX.csproj
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
-        <TargetFrameworks>net35;net6.0</TargetFrameworks>
+        <TargetFrameworks>net35;net40;net6.0</TargetFrameworks>
         <ProjectGuid>{78A8B08C-C0E9-4BAC-9AF6-58D3A55C05C9}</ProjectGuid>
         <ApplicationVersion>4.8.0.0</ApplicationVersion>
         <OutputType>Library</OutputType>