diff --git a/src/functions/TestDrive.ps1 b/src/functions/TestDrive.ps1
index 59cfd7146..e1374f33f 100644
--- a/src/functions/TestDrive.ps1
+++ b/src/functions/TestDrive.ps1
@@ -125,7 +125,8 @@ function Clear-TestDrive {
 function New-RandomTempDirectory {
     do {
         $tempPath = Get-TempDirectory
-        $Path = [IO.Path]::Combine($tempPath, ([Guid]::NewGuid()));
+        $dirName = 'Pester_' + [IO.Path]::GetRandomFileName().Substring(0, 4)
+        $Path = [IO.Path]::Combine($tempPath, $dirName)
     } until (-not [IO.Directory]::Exists($Path))
 
     [IO.Directory]::CreateDirectory($Path).FullName
diff --git a/src/functions/TestRegistry.ps1 b/src/functions/TestRegistry.ps1
index e821b8b4c..3208d1be3 100644
--- a/src/functions/TestRegistry.ps1
+++ b/src/functions/TestRegistry.ps1
@@ -73,7 +73,7 @@ function Get-TestRegistryChildItem ([string]$TestRegistryPath) {
 function New-RandomTempRegistry {
     do {
         $tempPath = Get-TempRegistry
-        $Path = & $SafeCommands['Join-Path'] -Path $tempPath -ChildPath ([Guid]::NewGuid())
+        $Path = & $SafeCommands['Join-Path'] -Path $tempPath -ChildPath ([IO.Path]::GetRandomFileName().Substring(0, 4))
     } until (-not (& $SafeCommands['Test-Path'] -Path $Path -PathType Container))
 
     try {