diff --git a/lib/csharp/ThriftMSBuildTask/ThriftMSBuildTask.csproj b/lib/csharp/ThriftMSBuildTask/ThriftMSBuildTask.csproj
index 1148eaa..ae86081 100644
--- a/lib/csharp/ThriftMSBuildTask/ThriftMSBuildTask.csproj
+++ b/lib/csharp/ThriftMSBuildTask/ThriftMSBuildTask.csproj
@@ -28,7 +28,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>ThriftMSBuildTask</RootNamespace>
     <AssemblyName>ThriftMSBuildTask</AssemblyName>
-    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <FileUpgradeFlags>
     </FileUpgradeFlags>