diff --git a/ConfForm.cs b/ConfForm.cs
index 6e93b70..8e112ee 100644
--- a/ConfForm.cs
+++ b/ConfForm.cs
@@ -17,11 +17,11 @@ namespace PDF_Merge
         {
             InitializeComponent();
 
-            string sourcePath = ConfigurationManager.AppSettings["PDF-Path"];
-            string outputPath = ConfigurationManager.AppSettings["PDF-Output"];
-            string outputName = ConfigurationManager.AppSettings["PDF-Name"];
-            string outputExt = ConfigurationManager.AppSettings["PDF-Extension"];
-            string dateIndex = ConfigurationManager.AppSettings["dateIndex"];
+            string sourcePath = ConfigurationManager.AppSettings["PDF-Path"] ?? "";
+            string outputPath = ConfigurationManager.AppSettings["PDF-Output"] ?? "";
+            string outputName = ConfigurationManager.AppSettings["PDF-Name"] ?? "merged";
+            string outputExt = ConfigurationManager.AppSettings["PDF-Extension"] ?? ".pdf";
+            string dateIndex = ConfigurationManager.AppSettings["dateIndex"] ?? "0";
 
             int dateIndexValue;