diff --git a/build.ps1 b/build.ps1
index 8887f8f..c76be82 100644
--- a/build.ps1
+++ b/build.ps1
@@ -40,6 +40,7 @@ param(
                 @()
             }
         })]
+    [ValidateNotNullOrEmpty()]
     [string[]]$Task = 'default',
 
     # Bootstrap dependencies