diff --git a/OpenRA.Game/OpenRA.Game.csproj b/OpenRA.Game/OpenRA.Game.csproj
index cfea2b55a6..be42bb84fe 100644
--- a/OpenRA.Game/OpenRA.Game.csproj
+++ b/OpenRA.Game/OpenRA.Game.csproj
@@ -43,6 +43,7 @@
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <StartArguments>Game.Mod=ra</StartArguments>
     <Commandlineparameters>Game.Mod=ra</Commandlineparameters>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
diff --git a/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj b/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
index 59cb4a691c..ea5ca9273c 100644
--- a/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
+++ b/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj
@@ -41,6 +41,7 @@
     <OutputPath>bin\Debug\</OutputPath>
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
@@ -213,4 +214,4 @@
     <Message Text="DEBUG TargetName:             $(TargetName)"/>
     -->
   </Target>
-</Project>
+</Project>
\ No newline at end of file
diff --git a/OpenRA.Mods.Common/OpenRA.Mods.Common.csproj b/OpenRA.Mods.Common/OpenRA.Mods.Common.csproj
index 15474ec6a7..5552b53883 100644
--- a/OpenRA.Mods.Common/OpenRA.Mods.Common.csproj
+++ b/OpenRA.Mods.Common/OpenRA.Mods.Common.csproj
@@ -24,6 +24,7 @@
     <PlatformTarget>x86</PlatformTarget>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
@@ -859,4 +860,4 @@
     <Message Text="DEBUG TargetName:             $(TargetName)"/>
     -->
   </Target>
-</Project>
+</Project>
\ No newline at end of file
diff --git a/OpenRA.Mods.D2k/OpenRA.Mods.D2k.csproj b/OpenRA.Mods.D2k/OpenRA.Mods.D2k.csproj
index 15c3128017..bfed6c8eec 100644
--- a/OpenRA.Mods.D2k/OpenRA.Mods.D2k.csproj
+++ b/OpenRA.Mods.D2k/OpenRA.Mods.D2k.csproj
@@ -42,6 +42,7 @@
     <DefineConstants>TRACE;DEBUG;</DefineConstants>
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
@@ -144,4 +145,4 @@
     <Message Text="DEBUG TargetName:             $(TargetName)"/>
     -->
   </Target>
-</Project>
+</Project>
\ No newline at end of file
diff --git a/OpenRA.Platforms.Default/OpenRA.Platforms.Default.csproj b/OpenRA.Platforms.Default/OpenRA.Platforms.Default.csproj
index 2ed721caaa..d9dff01017 100644
--- a/OpenRA.Platforms.Default/OpenRA.Platforms.Default.csproj
+++ b/OpenRA.Platforms.Default/OpenRA.Platforms.Default.csproj
@@ -20,6 +20,7 @@
     <ErrorReport>prompt</ErrorReport>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
diff --git a/OpenRA.Server/OpenRA.Server.csproj b/OpenRA.Server/OpenRA.Server.csproj
index e1a0a50c7b..fa028ac0ad 100644
--- a/OpenRA.Server/OpenRA.Server.csproj
+++ b/OpenRA.Server/OpenRA.Server.csproj
@@ -42,6 +42,7 @@
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
     <PlatformTarget>x86</PlatformTarget>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
diff --git a/OpenRA.StyleCheck/OpenRA.StyleCheck.csproj b/OpenRA.StyleCheck/OpenRA.StyleCheck.csproj
index c06e6f8da2..2aadf9e433 100644
--- a/OpenRA.StyleCheck/OpenRA.StyleCheck.csproj
+++ b/OpenRA.StyleCheck/OpenRA.StyleCheck.csproj
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -19,6 +19,7 @@
     <WarningLevel>4</WarningLevel>
     <ExternalConsole>true</ExternalConsole>
     <PlatformTarget>x86</PlatformTarget>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
     <Optimize>true</Optimize>
diff --git a/OpenRA.Test/OpenRA.Test.csproj b/OpenRA.Test/OpenRA.Test.csproj
index e451d7c9fd..7dc5bc112a 100644
--- a/OpenRA.Test/OpenRA.Test.csproj
+++ b/OpenRA.Test/OpenRA.Test.csproj
@@ -20,6 +20,7 @@
     <PlatformTarget>x86</PlatformTarget>
     <ErrorReport>prompt</ErrorReport>
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>
diff --git a/OpenRA.Utility/OpenRA.Utility.csproj b/OpenRA.Utility/OpenRA.Utility.csproj
index 34b8977c49..a287b48833 100644
--- a/OpenRA.Utility/OpenRA.Utility.csproj
+++ b/OpenRA.Utility/OpenRA.Utility.csproj
@@ -42,6 +42,7 @@
     <CodeAnalysisRuleSet>AllRules.ruleset</CodeAnalysisRuleSet>
     <PlatformTarget>x86</PlatformTarget>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
     <DebugSymbols>true</DebugSymbols>