diff --git a/tools/Build/Program.cs b/tools/Build/Program.cs
index b5c8140..415b512 100644
--- a/tools/Build/Program.cs
+++ b/tools/Build/Program.cs
@@ -18,7 +18,8 @@ internal static class Build
 			{
 				var projectPath = Path.Combine("src", "Twain.Web", "Twain.Web.csproj");
 
-				DeleteDirectory(artifactDirOption.Value);
+				if (artifactDirOption.Value != null)
+					DeleteDirectory(artifactDirOption.Value);
 
 				RunDotNet(new[]
 					{