diff --git a/Greenshot/Greenshot.csproj b/Greenshot/Greenshot.csproj
index 40623cf9c..fc731af53 100644
--- a/Greenshot/Greenshot.csproj
+++ b/Greenshot/Greenshot.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0">
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="3.5">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{CD642BF4-D815-4D67-A0B5-C69F0B8231AF}</ProjectGuid>
diff --git a/GreenshotConfluencePlugin/GreenshotConfluencePlugin.csproj b/GreenshotConfluencePlugin/GreenshotConfluencePlugin.csproj
index e9e83c771..55932be97 100644
--- a/GreenshotConfluencePlugin/GreenshotConfluencePlugin.csproj
+++ b/GreenshotConfluencePlugin/GreenshotConfluencePlugin.csproj
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-	<Import Project="..\CommonProject.properties" />
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{C3052651-598A-44E2-AAB3-2E41311D50F9}</ProjectGuid>
     <OutputType>Library</OutputType>
diff --git a/GreenshotExternalCommandPlugin/GreenshotExternalCommandPlugin.csproj b/GreenshotExternalCommandPlugin/GreenshotExternalCommandPlugin.csproj
index 077ca6ed2..6bff7298f 100644
--- a/GreenshotExternalCommandPlugin/GreenshotExternalCommandPlugin.csproj
+++ b/GreenshotExternalCommandPlugin/GreenshotExternalCommandPlugin.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{47F23C86-604E-4CC3-8767-B3D4088F30BB}</ProjectGuid>
diff --git a/GreenshotImgurPlugin/GreenshotImgurPlugin.csproj b/GreenshotImgurPlugin/GreenshotImgurPlugin.csproj
index 5067f8541..7044417df 100644
--- a/GreenshotImgurPlugin/GreenshotImgurPlugin.csproj
+++ b/GreenshotImgurPlugin/GreenshotImgurPlugin.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{80D8DEB9-94E3-4876-8CCA-2DF1ED5F2C50}</ProjectGuid>
diff --git a/GreenshotJiraPlugin/GreenshotJiraPlugin.csproj b/GreenshotJiraPlugin/GreenshotJiraPlugin.csproj
index fc632f75b..0e8695fc4 100644
--- a/GreenshotJiraPlugin/GreenshotJiraPlugin.csproj
+++ b/GreenshotJiraPlugin/GreenshotJiraPlugin.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{19FEEF09-313F-43C7-819D-F1BCA782B08B}</ProjectGuid>
diff --git a/GreenshotOCRCommand/GreenshotOCRCommand.csproj b/GreenshotOCRCommand/GreenshotOCRCommand.csproj
index 71a7be69b..ccbaa80d7 100644
--- a/GreenshotOCRCommand/GreenshotOCRCommand.csproj
+++ b/GreenshotOCRCommand/GreenshotOCRCommand.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
diff --git a/GreenshotOCRPlugin/GreenshotOCRPlugin.csproj b/GreenshotOCRPlugin/GreenshotOCRPlugin.csproj
index 015b4e820..ea5880a2c 100644
--- a/GreenshotOCRPlugin/GreenshotOCRPlugin.csproj
+++ b/GreenshotOCRPlugin/GreenshotOCRPlugin.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{C6988EE8-2FEE-4349-9F09-F9628A0D8965}</ProjectGuid>
diff --git a/GreenshotPlugin/GreenshotPlugin.csproj b/GreenshotPlugin/GreenshotPlugin.csproj
index 5437a720c..46fe39550 100644
--- a/GreenshotPlugin/GreenshotPlugin.csproj
+++ b/GreenshotPlugin/GreenshotPlugin.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\CommonProject.properties" />
   <PropertyGroup>
     <ProjectGuid>{5B924697-4DCD-4F98-85F1-105CB84B7341}</ProjectGuid>