diff --git a/src/System.Collections.Immutable/src/System.Collections.Immutable.csproj b/src/System.Collections.Immutable/src/System.Collections.Immutable.csproj
index c90c76d08a58..6ef0ddf1e178 100644
--- a/src/System.Collections.Immutable/src/System.Collections.Immutable.csproj
+++ b/src/System.Collections.Immutable/src/System.Collections.Immutable.csproj
@@ -1,13 +1,10 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
-  
-  
   <PropertyGroup>
     <!-- Work around known Dev14 bug - see
          https://connect.microsoft.com/VisualStudio/feedback/details/1000796/connect-file-uap-props-not-found-cant-build-a-portable-lib-on-vs14
-    --> 
-     
+    -->
     <_WindowsKitBinPath>C:\Program Files (x86)\Windows Kits\8.1\bin\x86</_WindowsKitBinPath>
     <_WindowsPhoneKitBinPath>C:\Program Files (x86)\Windows Phone Kits\8.1\bin</_WindowsPhoneKitBinPath>
     <MakePriExeFullPath>$(_WindowsKitBinPath)\makepri.exe</MakePriExeFullPath>
@@ -16,8 +13,6 @@
     <MakePriExtensionPath>$(_WindowsPhoneKitBinPath)\x86\MrmEnvironmentExtDl.dll</MakePriExtensionPath>
     <MakePriExtensionPath_x64>$(_WindowsPhoneKitBinPath)\x64\MrmEnvironmentExtDl.dll</MakePriExtensionPath_x64>
   </PropertyGroup>
-  
-  
   <PropertyGroup>
     <MinimumVisualStudioVersion>10.0</MinimumVisualStudioVersion>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -48,7 +43,7 @@
     <WarningLevel>4</WarningLevel>
     <Prefer32Bit>false</Prefer32Bit>
     <CodeAnalysisRuleSet>System.Collections.Immutable.ruleset</CodeAnalysisRuleSet>
-    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <AllowUnsafeBlocks>false</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
@@ -119,7 +114,6 @@
     <Compile Include="System\Diagnostics\CodeAnalysis\ExcludeFromCodeCoverageAttribute.cs" />
     <Compile Include="System\Linq\ImmutableArrayExtensions.cs" />
     <Compile Include="System\Runtime\InteropServices\ImmutableArrayInterop.cs" />
-
     <Compile Include="Strings.Designer.cs">
       <AutoGen>True</AutoGen>
       <DesignTime>True</DesignTime>
@@ -155,4 +149,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>
\ No newline at end of file