diff --git a/tools/appveyor.psm1 b/tools/appveyor.psm1
index cc8e15f81..ea4d4362e 100644
--- a/tools/appveyor.psm1
+++ b/tools/appveyor.psm1
@@ -35,8 +35,15 @@ function Invoke-AppVeyorInstall {
     $dotNetCoreSDKVersion = $globalDotJson.sdk.version
     # don't try to run this script on linux - we have to do the negative check because IsLinux will be defined in core, but not windows
     if (-not ((dotnet --version).StartsWith($dotNetCoreSDKVersion)) -and ! $IsLinux ) {
-        [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12 # https://github.com/dotnet/announcements/issues/77
-        Invoke-WebRequest 'https://dot.net/v1/dotnet-install.ps1' -OutFile dotnet-install.ps1
+        try {
+            $originalSecurityProtocol = [Net.ServicePointManager]::SecurityProtocol
+            # To avoid SSL error, see https://github.com/dotnet/announcements/issues/77 and https://github.com/PowerShell/PowerShell/pull/6236/files
+            [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12
+            Invoke-WebRequest 'https://dot.net/v1/dotnet-install.ps1' -OutFile dotnet-install.ps1
+        }
+        finally {
+            [Net.ServicePointManager]::SecurityProtocol = $originalSecurityProtocol
+        }
         .\dotnet-install.ps1 -Version $dotNetCoreSDKVersion
         Remove-Item .\dotnet-install.ps1
     }