diff --git a/build/pack-extensions.ps1 b/build/pack-extensions.ps1
index f3fb164e35..1d0a3f01cc 100644
--- a/build/pack-extensions.ps1
+++ b/build/pack-extensions.ps1
@@ -57,6 +57,13 @@ function Pack-SelfContained() {
         [string] $PackageData = $null
     );
 
+    Write-Host "##[info]Building $project ($action)..."
+    if ("" -ne "$Env:ASSEMBLY_CONSTANTS") {
+        $args = @("/property:DefineConstants=$Env:ASSEMBLY_CONSTANTS");
+    }  else {
+        $args = @();
+    }
+
     # Make sure the LanguageServer is built on its own:
     dotnet build (Join-Path $PSScriptRoot $project) `
         -c $Env:BUILD_CONFIGURATION `