diff --git a/spine-monogame/xamarinstudio-ios/src/spine-monogame-xamarinstudio-ios.csproj b/spine-monogame/xamarinstudio-ios/src/spine-monogame-xamarinstudio-ios.csproj
index 9fa0e1033..b116e6660 100644
--- a/spine-monogame/xamarinstudio-ios/src/spine-monogame-xamarinstudio-ios.csproj
+++ b/spine-monogame/xamarinstudio-ios/src/spine-monogame-xamarinstudio-ios.csproj
@@ -29,6 +29,7 @@
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <ConsolePause>false</ConsolePause>
+    <DefineConstants>IOS</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />