diff --git a/ControlPad.Tests/ControlPad.Tests.csproj b/ControlPad.Tests/ControlPad.Tests.csproj
index a4531a8..a8178ae 100644
--- a/ControlPad.Tests/ControlPad.Tests.csproj
+++ b/ControlPad.Tests/ControlPad.Tests.csproj
@@ -20,6 +20,7 @@
 
   <ItemGroup>
     <Compile Include="../ControlPad/AudioStream.cs" Link="Source/AudioStream.cs" />
+    <Compile Include="../ControlPad/System/ProcessIdentifierHelper.cs" Link="Source/ProcessIdentifierHelper.cs" />
     <Compile Include="../ControlPad/ActionType.cs" Link="Source/ActionType.cs" />
     <Compile Include="../ControlPad/ButtonAction.cs" Link="Source/ButtonAction.cs" />
     <Compile Include="../ControlPad/ButtonCategory.cs" Link="Source/ButtonCategory.cs" />