diff --git a/RombaSharp/Features/Diffdat.cs b/RombaSharp/Features/Diffdat.cs
index 1071fddb..8eaa80c0 100644
--- a/RombaSharp/Features/Diffdat.cs
+++ b/RombaSharp/Features/Diffdat.cs
@@ -45,7 +45,7 @@ in -old DAT file. Ignores those entries in -old that are not in -new.";
             string? outdat = GetString(features, OutStringValue);
 
             // Ensure the output directory
-            outdat = outdat?.Ensure(create: true);
+            outdat = (outdat ?? string.Empty).Ensure(create: true);
 
             // Check that all required files exist
             if (!File.Exists(olddat))
diff --git a/RombaSharp/Features/Dir2Dat.cs b/RombaSharp/Features/Dir2Dat.cs
index f7ee6adf..8b581e57 100644
--- a/RombaSharp/Features/Dir2Dat.cs
+++ b/RombaSharp/Features/Dir2Dat.cs
@@ -44,7 +44,7 @@ namespace RombaSharp.Features
             string? outdat = GetString(features, OutStringValue);
 
             // Ensure the output directory
-            outdat = outdat?.Ensure(create: true);
+            outdat = (outdat ?? string.Empty).Ensure(create: true);
 
             // Check that all required directories exist
             if (!Directory.Exists(source))
diff --git a/RombaSharp/Features/EDiffdat.cs b/RombaSharp/Features/EDiffdat.cs
index b9f0458e..9fdd9618 100644
--- a/RombaSharp/Features/EDiffdat.cs
+++ b/RombaSharp/Features/EDiffdat.cs
@@ -40,7 +40,7 @@ namespace RombaSharp.Features
             string? newdat = GetString(features, NewStringValue);
 
             // Ensure the output directory
-            outdat = outdat?.Ensure(create: true);
+            outdat = (outdat ?? string.Empty).Ensure(create: true);
 
             // Check that all required files exist
             if (!File.Exists(olddat))
diff --git a/SabreTools.DatTools/Statistics.cs b/SabreTools.DatTools/Statistics.cs
index 2054b79f..71d098b3 100644
--- a/SabreTools.DatTools/Statistics.cs
+++ b/SabreTools.DatTools/Statistics.cs
@@ -171,7 +171,7 @@ namespace SabreTools.DatTools
                 reportName = "report";
 
             // Get the proper output directory name
-            outDir = outDir?.Ensure();
+            outDir = (outDir ?? string.Empty).Ensure();
 
             InternalStopwatch watch = new($"Writing out report data to '{outDir}'");
 
diff --git a/SabreTools.DatTools/Writer.cs b/SabreTools.DatTools/Writer.cs
index 3fa5c837..883261e2 100644
--- a/SabreTools.DatTools/Writer.cs
+++ b/SabreTools.DatTools/Writer.cs
@@ -39,7 +39,7 @@ namespace SabreTools.DatTools
         /// <returns>True if the DAT was written correctly, false otherwise</returns>
         public static bool Write(
             DatFile datFile,
-            string ?outDir,
+            string? outDir,
             bool overwrite = true,
             bool ignoreblanks = false,
             bool quotes = true,
@@ -53,7 +53,7 @@ namespace SabreTools.DatTools
             }
 
             // Ensure the output directory is set and created
-            outDir = outDir?.Ensure(create: true);
+            outDir = (outDir ?? string.Empty).Ensure(create: true);
 
             InternalStopwatch watch = new($"Writing out internal dat to '{outDir}'");
 
diff --git a/SabreTools/Features/Split.cs b/SabreTools/Features/Split.cs
index 50d7d412..386807b4 100644
--- a/SabreTools/Features/Split.cs
+++ b/SabreTools/Features/Split.cs
@@ -68,7 +68,7 @@ namespace SabreTools.Features
                 Parser.ParseInto(internalDat, file);
 
                 // Get the output directory
-                OutputDir = OutputDir?.Ensure();
+                OutputDir = (OutputDir ?? string.Empty).Ensure();
                 OutputDir = file.GetOutputPath(OutputDir, GetBoolean(features, InplaceValue));
 
                 // Extension splitting
diff --git a/SabreTools/Features/Update.cs b/SabreTools/Features/Update.cs
index 19ab16a1..d696ae41 100644
--- a/SabreTools/Features/Update.cs
+++ b/SabreTools/Features/Update.cs
@@ -149,7 +149,7 @@ namespace SabreTools.Features
             List<ParentablePath> basePaths = PathTool.GetFilesOnly(GetList(features, BaseDatListValue));
 
             // Ensure the output directory
-            OutputDir = OutputDir?.Ensure();
+            OutputDir = (OutputDir ?? string.Empty).Ensure();
 
             // If we're in standard update mode, run through all of the inputs
             if (updateMode == UpdateMode.None)