diff --git a/scripts/vsts-prebuild.ps1 b/scripts/vsts-prebuild.ps1
index 57ceae1ac8..ba170867ad 100644
--- a/scripts/vsts-prebuild.ps1
+++ b/scripts/vsts-prebuild.ps1
@@ -19,7 +19,7 @@ if ($IsRtmBuild.ToLower() -eq "false")
 { 
   if ($null -ne $Branch -and $Branch -like "refs/heads/rel/*")
   { 
-    $BuildSuffix -replace "preview", "release"
+    $BuildSuffix = $BuildSuffix -replace "preview", "release"
   }
 
   $packageVersion = $buildPrefix+"-"+$buildSuffix