diff --git a/ObservatoryCore/ObservatoryCore.csproj b/ObservatoryCore/ObservatoryCore.csproj
index 65ee657..148c7d9 100644
--- a/ObservatoryCore/ObservatoryCore.csproj
+++ b/ObservatoryCore/ObservatoryCore.csproj
@@ -67,8 +67,8 @@
   <Target Name="PreBuild" BeforeTargets="PreBuildEvent">
     <Exec Condition=" '$(OS)' == 'Windows_NT'" Command="if not exist &quot;$(ProjectDir)..\ObservatoryFramework\bin\Release\net5.0\ObservatoryFramework.dll&quot; dotnet build &quot;$(ProjectDir)..\ObservatoryFramework\ObservatoryFramework.csproj&quot; -c Release" />
     <Exec Condition=" '$(OS)' == 'Windows_NT'" Command="if not exist &quot;$(OutDir)plugins\ObservatoryExplorer.dll&quot; dotnet build &quot;$(ProjectDir)..\ObservatoryExplorer\ObservatoryExplorer.csproj&quot; -c $(ConfigurationName)" />
-    <Exec Condition=" '$(OS)' != 'Windows_NT'" Command="[ -e &quot;$(ProjectDir)../ObservatoryFramework/bin/Release/net5.0/ObservatoryFramework.dll&quot; ] &amp;&amp; dotnet build &quot;$(ProjectDir)../ObservatoryFramework/ObservatoryFramework.csproj&quot; -c Release" />
-    <Exec Condition=" '$(OS)' != 'Windows_NT'" Command="[ -e &quot;$(OutDir)plugins/ObservatoryExplorer.dll&quot; ] &amp;&amp; dotnet build &quot;$(ProjectDir)../ObservatoryExplorer/ObservatoryExplorer.csproj&quot; -c $(ConfigurationName)" />
+    <Exec Condition=" '$(OS)' != 'Windows_NT'" Command="[ ! -e &quot;$(ProjectDir)../ObservatoryFramework/bin/Release/net5.0/ObservatoryFramework.dll&quot; ] &amp;&amp; dotnet build &quot;$(ProjectDir)../ObservatoryFramework/ObservatoryFramework.csproj&quot; -c Release" />
+    <Exec Condition=" '$(OS)' != 'Windows_NT'" Command="[ ! -e &quot;$(OutDir)plugins/ObservatoryExplorer.dll&quot; ] &amp;&amp; dotnet build &quot;$(ProjectDir)../ObservatoryExplorer/ObservatoryExplorer.csproj&quot; -c $(ConfigurationName)" />
   </Target>
 
 </Project>