diff --git a/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj b/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
index cf6f8c3ed1..d1e0800e75 100644
--- a/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
+++ b/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
@@ -384,6 +384,7 @@
     <Compile Include="World\PlayMusicOnMapLoad.cs" />
     <Compile Include="World\SmudgeLayer.cs" />
     <Compile Include="Player\BaseAttackNotifier.cs" />
+    <Compile Include="Player\HarvesterAttackNotifier.cs" />
     <Compile Include="InfiltrateForExploration.cs" />
     <Compile Include="InfiltrateForCash.cs" />
     <Compile Include="RenderShroudCircle.cs" />