diff --git a/thor-seed/thor-seed.ps1 b/thor-seed/thor-seed.ps1
index d333e38..61b39a4 100644
--- a/thor-seed/thor-seed.ps1
+++ b/thor-seed/thor-seed.ps1
@@ -196,6 +196,29 @@ param
     $ProxyCredentials = [System.Management.Automation.PSCredential]::Empty
 )
 
+# THOR Seed requires FullLanguage mode because it uses .NET APIs for TLS,
+# download handling, ZIP extraction, and process setup.
+$LanguageMode = $ExecutionContext.SessionState.LanguageMode.ToString()
+if ($LanguageMode -ne "FullLanguage")
+{
+    Write-Host ""
+    Write-Host "===========================================================" -ForegroundColor Red
+    Write-Host " ERROR: Unsupported PowerShell Language Mode detected" -ForegroundColor Red
+    Write-Host "===========================================================" -ForegroundColor Red
+    Write-Host ""
+    Write-Host "Current Language Mode : $LanguageMode"
+    Write-Host ""
+    Write-Host "THOR Seed requires FullLanguage mode and cannot continue."
+    Write-Host "This is commonly caused by App Control for Business / WDAC,"
+    Write-Host "AppLocker, JEA, or endpoint security policy restrictions."
+    Write-Host ""
+    Write-Host "Allow or sign thor-seed.ps1 according to your policy and rerun it."
+    Write-Host "Reference: https://learn.microsoft.com/en-us/windows/security/application-security/application-control/app-control-for-business/design/script-enforcement"
+    Write-Host ""
+
+    exit 7
+}
+
 # #####################################################################
 # Presets -------------------------------------------------------------
 # #####################################################################