diff --git a/libsodium.vcxproj b/libsodium.vcxproj
index 25163806..845df9d2 100644
--- a/libsodium.vcxproj
+++ b/libsodium.vcxproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup Label="ProjectConfigurations">
     <ProjectConfiguration Include="DebugDLL|Win32">
       <Configuration>DebugDLL</Configuration>
@@ -45,56 +45,56 @@
     <UseDebugLibraries>true</UseDebugLibraries>
     <CharacterSet>MultiByte</CharacterSet>
     <WholeProgramOptimization>false</WholeProgramOptimization>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='DebugDLL|Win32'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <CharacterSet>MultiByte</CharacterSet>
     <WholeProgramOptimization>false</WholeProgramOptimization>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
     <ConfigurationType>StaticLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <CharacterSet>MultiByte</CharacterSet>
     <WholeProgramOptimization>false</WholeProgramOptimization>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='DebugDLL|x64'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <CharacterSet>MultiByte</CharacterSet>
     <WholeProgramOptimization>false</WholeProgramOptimization>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
     <ConfigurationType>StaticLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='ReleaseDLL|Win32'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
     <ConfigurationType>StaticLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='ReleaseDLL|x64'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v140</PlatformToolset>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
   <ImportGroup Label="ExtensionSettings">
@@ -548,4 +548,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>