diff --git a/requirements.psd1 b/requirements.psd1
index c7e5de0..3f920f5 100755
--- a/requirements.psd1
+++ b/requirements.psd1
@@ -9,7 +9,7 @@
             SkipPublisherCheck = $true
         }
     }
-    psake            = '4.9.0'
+    psake            = '5.0.4'
     PSScriptAnalyzer = '1.25.0'
     InvokeBuild      = '5.14.23'
     platyPS          = '0.14.2'
diff --git a/tests/Manifest.tests.ps1 b/tests/Manifest.tests.ps1
index b659654..4150b20 100644
--- a/tests/Manifest.tests.ps1
+++ b/tests/Manifest.tests.ps1
@@ -1,5 +1,10 @@
 BeforeAll {
-    Set-BuildEnvironment -Force
+    # Only call Set-BuildEnvironment when the build variables are not already present.
+    # build.ps1 sets them before Invoke-psake, so inside a build this is a no-op; standalone
+    # Pester runs still get them. Calling it unconditionally lets an escaping 'break' from
+    # BuildHelpers' Get-BuildVariable switch blocks unwind out of this BeforeAll, which
+    # psake 4.9.x absorbs but psake 5.x does not -- Pester then fails the whole container.
+    if (-not $env:BHProjectName) { Set-BuildEnvironment -Force }
     $moduleName         = $env:BHProjectName
     $manifest           = Import-PowerShellDataFile -Path $env:BHPSModuleManifest
     $outputDir          = Join-Path -Path $ENV:BHProjectPath -ChildPath 'Output'