diff --git a/src/FSharpPortable/FSharpPortable.fsproj b/src/FSharpPortable/FSharpPortable.fsproj
index aff5bc54..8490eca6 100644
--- a/src/FSharpPortable/FSharpPortable.fsproj
+++ b/src/FSharpPortable/FSharpPortable.fsproj
@@ -19,7 +19,7 @@
     <Optimize>false</Optimize>
     <Tailcalls>false</Tailcalls>
     <OutputPath>..\..\out\debug\Portable\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;PORTABLE</DefineConstants>
     <WarningLevel>3</WarningLevel>
     <DocumentationFile>
     </DocumentationFile>