diff --git a/bin/BuildTool/Module.cs b/bin/BuildTool/Module.cs
index 1c857ca..b8a81a8 100644
--- a/bin/BuildTool/Module.cs
+++ b/bin/BuildTool/Module.cs
@@ -79,22 +79,7 @@ abstract class Module
                 // Since we don't save anything directory specific in the has, we can skip this check if we already know that we are going to rebuild.
                 if (!needsRebuild)
                 {
-                    foreach (FileSystemInfo dirEntry in dirInfo.EnumerateFileSystemInfos("**",
-                                 enumerationOptions: new EnumerationOptions()
-                                     { MatchType = MatchType.Win32, RecurseSubdirectories = source.Recursive }))
-                    {
-                        //string relativePath = Path.GetRelativePath(dirInfo.FullName, dirEntry.FullName);
-                        //if (source.ExcludedDirectories.Contains(relativePath, StringComparer.OrdinalIgnoreCase))
-                        //    continue;
-
-                        Console.WriteLine("Checking entry: " + dirEntry.FullName);
-                        if (dirEntry.LastWriteTimeUtc > cacheInfo.LastSuccessfulBuild)
-                        {
-                            Console.WriteLine("Needs rebuild");
-                            needsRebuild = true;
-                            break;
-                        }
-                    }
+                    needsRebuild = DirectoryNeedsRebuild(cacheInfo, dirInfo, source, needsRebuild);
                 }
 
                 // We really just need any timestamp, to know that the directory existed at some point.
@@ -152,6 +137,40 @@ abstract class Module
         return needsRebuild;
     }
 
+    private static bool DirectoryNeedsRebuild(ModuleInfo cacheInfo, DirectoryInfo dirInfo, WatchedSource source,
+        bool needsRebuild)
+    {
+        Stack<DirectoryInfo> directoriesToCheck = new ();
+        directoriesToCheck.Push(dirInfo);
+
+        while (directoriesToCheck.Count > 0)
+        {
+            DirectoryInfo directory = directoriesToCheck.Pop();
+            
+            foreach (FileSystemInfo dirEntry in directory.EnumerateFileSystemInfos())
+            {
+                string relativePath = Path.GetRelativePath(dirInfo.FullName, dirEntry.FullName);
+                if (source.ExcludedSubpaths.Contains(relativePath, StringComparer.OrdinalIgnoreCase))
+                    continue;
+
+                if (dirEntry.Attributes.HasFlag(FileAttributes.Directory))
+                {
+                    directoriesToCheck.Push(new DirectoryInfo(dirEntry.FullName));
+                }
+
+                Console.WriteLine("Checking entry: " + dirEntry.FullName);
+                if (dirEntry.LastWriteTimeUtc > cacheInfo.LastSuccessfulBuild)
+                {
+                    Console.WriteLine("Needs rebuild");
+                    needsRebuild = true;
+                    break;
+                }
+            }
+        }
+
+        return needsRebuild;
+    }
+
     private static string ComputeFileHash(string filePath)
     {
         using var stream = File.OpenRead(filePath);
diff --git a/bin/BuildTool/Modules/ScriptCoreModule.cs b/bin/BuildTool/Modules/ScriptCoreModule.cs
index 436d612..2366e59 100644
--- a/bin/BuildTool/Modules/ScriptCoreModule.cs
+++ b/bin/BuildTool/Modules/ScriptCoreModule.cs
@@ -38,7 +38,7 @@ class ScriptCoreModule : Module
         sources.Add(new WatchedSource("ScriptCore/", WatchMode.Metadata)
         {
             Recursive = true,
-            ExcludedDirectories =
+            ExcludedSubpaths =
             [
                 "bin",
                 "obj"
diff --git a/bin/BuildTool/WatchedSource.cs b/bin/BuildTool/WatchedSource.cs
index ca2f5fb..9092acb 100644
--- a/bin/BuildTool/WatchedSource.cs
+++ b/bin/BuildTool/WatchedSource.cs
@@ -27,7 +27,7 @@ internal record WatchedSource(string Path, WatchMode Mode)
     /// <summary>
     /// Only if Path points to a directory, a list of subdirectories to exclude from change checking.
     /// </summary>
-    public List<string> ExcludedDirectories { get; init; } = new();
+    public List<string> ExcludedSubpaths { get; init; } = new();
     /// <summary>
     /// Only if Path points to a directory, whether to check for changes in subdirectories as well.
     /// </summary>