diff --git a/.github/workflows/toolbox-alignment.yml b/.github/workflows/toolbox-alignment.yml
index aa886d7..e37f7c4 100644
--- a/.github/workflows/toolbox-alignment.yml
+++ b/.github/workflows/toolbox-alignment.yml
@@ -3,9 +3,9 @@ name: Standalone toolbox alignment
 on:
   push:
     branches: [master]
-    paths: ['New-StringConversion.ps1', 'Test-IsEmail.ps1', 'Test-IsValidDn.ps1', 'Get-ElapsedTime.ps1', 'Private/**', 'Tests/ToolboxAlignment.Tests.ps1', '.github/workflows/toolbox-alignment.yml']
+    paths: ['New-StringConversion.ps1', 'Test-IsEmail.ps1', 'Test-IsValidDn.ps1', 'Get-ElapsedTime.ps1', 'New-Timer.ps1', 'Stop-Timer.ps1', 'Get-TimerStatus.ps1', 'Private/**', 'Tests/ToolboxAlignment.Tests.ps1', 'Tests/Timer.Tests.ps1', '.github/workflows/toolbox-alignment.yml']
   pull_request:
-    paths: ['New-StringConversion.ps1', 'Test-IsEmail.ps1', 'Test-IsValidDn.ps1', 'Get-ElapsedTime.ps1', 'Private/**', 'Tests/ToolboxAlignment.Tests.ps1', '.github/workflows/toolbox-alignment.yml']
+    paths: ['New-StringConversion.ps1', 'Test-IsEmail.ps1', 'Test-IsValidDn.ps1', 'Get-ElapsedTime.ps1', 'New-Timer.ps1', 'Stop-Timer.ps1', 'Get-TimerStatus.ps1', 'Private/**', 'Tests/ToolboxAlignment.Tests.ps1', 'Tests/Timer.Tests.ps1', '.github/workflows/toolbox-alignment.yml']
   workflow_dispatch:
 
 permissions:
@@ -32,7 +32,7 @@ jobs:
           Install-Module Pester -RequiredVersion 5.7.1 -Scope CurrentUser -Force -Repository PSGallery
           Import-Module Pester -RequiredVersion 5.7.1 -Force
           $configuration = New-PesterConfiguration
-          $configuration.Run.Path = @('./Tests/New-ApiRequest.Tests.ps1', './Tests/ToolboxAlignment.Tests.ps1')
+          $configuration.Run.Path = @('./Tests/New-ApiRequest.Tests.ps1', './Tests/ToolboxAlignment.Tests.ps1', './Tests/Timer.Tests.ps1')
           $configuration.Run.Exit = $true
           $configuration.Output.Verbosity = 'Detailed'
           Invoke-Pester -Configuration $configuration
diff --git a/Get-TimerStatus.ps1 b/Get-TimerStatus.ps1
index cf7998e..5aec3b5 100644
--- a/Get-TimerStatus.ps1
+++ b/Get-TimerStatus.ps1
@@ -17,13 +17,15 @@ function Get-TimerStatus
             System.Boolean
     #>
 
+    [CmdletBinding()]
     [OutputType([bool])]
     param
     (
         [Parameter(Mandatory = $true)]
+        [ValidateNotNull()]
         [System.Diagnostics.Stopwatch]
         $Timer
     )
 
     return $Timer.IsRunning
-}
\ No newline at end of file
+}
diff --git a/Stop-Timer.ps1 b/Stop-Timer.ps1
index c480b5f..2997ee9 100644
--- a/Stop-Timer.ps1
+++ b/Stop-Timer.ps1
@@ -1,73 +1,36 @@
 function Stop-Timer
 {
     <#
-        .SYNOPSIS
-            Function will halt a stopwatch.
-
-        .DESCRIPTION
-            Function requires a [System.Diagnostics.Stopwatch] object as input and will invoke the stop() method to hald its execution.
-
-            If no exceptions are returned function will return $True.
-
-        .PARAMETER Timer
-            A [System.Diagnostics.Stopwatch] representing the stopwatch to stop.
-
-        .EXAMPLE
-            PS C:\> Stop-Timer -Timer $Timer
-
-        .OUTPUTS
-            System.Boolean
+    .SYNOPSIS
+        Stops a stopwatch without resetting its elapsed time.
+    .DESCRIPTION
+        Returns $true after stopping the supplied stopwatch. Stopping an already
+        stopped stopwatch also succeeds. Invalid input is rejected during binding.
+        If Stop() throws, reports a warning and returns $false.
+    .PARAMETER Timer
+        The stopwatch instance to stop.
+    .EXAMPLE
+        Stop-Timer -Timer $Timer
+    .OUTPUTS
+        System.Boolean
     #>
-
+    [CmdletBinding()]
     [OutputType([bool])]
-    param
-    (
+    param (
         [Parameter(Mandatory = $true)]
+        [ValidateNotNull()]
         [System.Diagnostics.Stopwatch]$Timer
     )
 
-    Begin
+    try
     {
-        # Save current configuration
-        [string]$currentConfig = $ErrorActionPreference
-
-        # Update configuration
-        $ErrorActionPreference = 'Stop'
+        $Timer.Stop()
+        return $true
     }
-
-    Process
-    {
-        try
-        {
-            # Stop timer
-            $Timer.Stop()
-
-            return $true
-        }
-        catch
-        {
-            # Save exception
-            [string]$reportedException = $Error[0].Exception.Message
-
-            Write-Warning -Message 'Exception reported while halting stopwatch - Use the -Verbose parameter for more details'
-
-            # Check we have an exception message
-            if ([string]::IsNullOrEmpty($reportedException) -eq $false)
-            {
-                Write-Verbose -Message $reportedException
-            }
-            else
-            {
-                Write-Verbose -Message 'No inner exception reported by Disconnect-AzureAD cmdlet'
-            }
-
-            return $false
-        }
-    }
-
-    End
+    catch
     {
-        # Revert back configuration
-        $ErrorActionPreference = $currentConfig
+        Write-Warning -Message 'Exception reported while stopping stopwatch; use -Verbose for details.'
+        Write-Verbose -Message $_.Exception.Message
+        return $false
     }
-}
\ No newline at end of file
+}
diff --git a/Tests/Timer.Tests.ps1 b/Tests/Timer.Tests.ps1
new file mode 100644
index 0000000..6051a05
--- /dev/null
+++ b/Tests/Timer.Tests.ps1
@@ -0,0 +1,46 @@
+BeforeAll {
+    foreach ($name in 'New-Timer','Stop-Timer','Get-TimerStatus','Get-ElapsedTime') {
+        . (Join-Path $PSScriptRoot "../$name.ps1")
+    }
+}
+Describe 'Stopwatch lifecycle' {
+    It 'starts, reports status, stops and preserves elapsed time' {
+        $timer=New-Timer
+        $timer | Should -BeOfType ([System.Diagnostics.Stopwatch])
+        Get-TimerStatus $timer | Should -BeTrue
+        [System.Threading.SpinWait]::SpinUntil([Func[bool]]{$timer.ElapsedTicks -gt 0},1000) | Should -BeTrue
+        Stop-Timer $timer | Should -BeTrue
+        Get-TimerStatus $timer | Should -BeFalse
+        $ticks=$timer.ElapsedTicks
+        $ticks | Should -BeGreaterThan 0
+        Stop-Timer $timer | Should -BeTrue
+        $timer.ElapsedTicks | Should -Be $ticks
+        (Get-ElapsedTime -ElapsedTime $timer).Ticks | Should -Be $timer.Elapsed.Ticks
+    }
+    It 'does not start a stopwatch that was never started' {
+        $timer=[System.Diagnostics.Stopwatch]::new()
+        Stop-Timer $timer | Should -BeTrue
+        Get-TimerStatus $timer | Should -BeFalse
+        $timer.ElapsedTicks | Should -Be 0
+    }
+    It 'rejects null and incompatible inputs' {
+        {Stop-Timer -Timer $null} | Should -Throw
+        {Get-TimerStatus -Timer $null} | Should -Throw
+        {Stop-Timer -Timer 'invalid'} | Should -Throw
+        {Get-TimerStatus -Timer 'invalid'} | Should -Throw
+    }
+    It 'preserves caller error preferences' {
+        $ErrorActionPreference='Continue'
+        $timer=New-Timer
+        Stop-Timer $timer | Should -BeTrue
+        $ErrorActionPreference | Should -Be 'Continue'
+        {Stop-Timer -Timer $null} | Should -Throw
+        $ErrorActionPreference | Should -Be 'Continue'
+    }
+    It 'accepts verbose diagnostics and returns a boolean' {
+        $timer=New-Timer
+        $result=Stop-Timer $timer -Verbose
+        $result | Should -BeOfType ([bool])
+        Get-TimerStatus $timer -Verbose | Should -BeFalse
+    }
+}