diff --git a/Program.cs b/Program.cs
index 90771f4..3f1ff07 100644
--- a/Program.cs
+++ b/Program.cs
@@ -1,9 +1,17 @@
-using System.Text.Json;
+using System.Reflection;
+using System.Text.Json;
 using s8n_runtime.ViewModels;
 
 string workflowViewFile = Environment.GetEnvironmentVariable("WORKFLOW_FILE")!;
 string projectDirectory = Environment.GetEnvironmentVariable("PROJECT_DIR") ?? $"/sources";
 
+if (string.IsNullOrEmpty(workflowViewFile) || !Directory.Exists(projectDirectory))
+{
+    AssemblyName a_name = Assembly.GetExecutingAssembly()!.GetName();
+    Console.WriteLine("S8N Compiler, version: {0}.\nSpecify environment variables: WORKFLOW_FILE, PROJECT_DIR.\nCLR: {1}", a_name.Version, Environment.Version);
+    return;
+}
+
 var workflow = JsonSerializer.Deserialize<S8nWorkflow>(File.OpenRead(workflowViewFile), JsonSerializerOptions.Web)!;
 
 var edgesFile = Path.Combine("/sources", $"{workflow.Name}.Edges.cs");