diff --git a/core/log/LogManager.cpp b/core/log/LogManager.cpp
index 2f6e6977c..f45e17ef9 100644
--- a/core/log/LogManager.cpp
+++ b/core/log/LogManager.cpp
@@ -138,7 +138,7 @@ LogManager::LogManager()
 		FileLogListener *listener = new FileLogListener(logPath);
 		if (!listener->IsValid())
 		{
-			const char *home = getenv("HOME");
+			const char *home = nowide::getenv("HOME");
 			if (home != nullptr)
 			{
 				delete listener;
diff --git a/core/oslib/directory.h b/core/oslib/directory.h
index 6640a52dd..3924b9bf7 100644
--- a/core/oslib/directory.h
+++ b/core/oslib/directory.h
@@ -125,3 +125,133 @@ inline int mkdir(const char *path, mode_t mode) {
 #endif
 }
 
+// iterate depth-first over the files contained in a folder hierarchy
+class DirectoryTree
+{
+public:
+	struct item {
+		std::string name;
+		std::string parentPath;
+	};
+
+	class iterator
+	{
+	private:
+		iterator(DIR *dir, std::string pathname) {
+			if (dir != nullptr)
+			{
+				dirs.push_back(dir);
+				pathnames.push_back(pathname);
+				advance();
+			}
+		}
+
+	public:
+		~iterator() {
+			for (DIR *dir : dirs)
+				flycast::closedir(dir);
+		}
+
+		const item *operator->() {
+			if (direntry == nullptr)
+				throw std::runtime_error("null iterator");
+			return &currentItem;
+		}
+
+		const item& operator*() const {
+			if (direntry == nullptr)
+				throw std::runtime_error("null iterator");
+			return currentItem;
+		}
+
+		// Prefix increment
+		iterator& operator++() {
+			advance();
+			return *this;
+		}
+
+		// Basic (in)equality implementations, just intended to work when comparing with end() or this
+		friend bool operator==(const iterator& a, const iterator& b) {
+			return a.direntry == b.direntry;
+		}
+
+		friend bool operator!=(const iterator& a, const iterator& b) {
+			return a.direntry != b.direntry;
+		}
+
+	private:
+		void advance()
+		{
+			while (!dirs.empty())
+			{
+				direntry = flycast::readdir(dirs.back());
+				if (direntry == nullptr)
+				{
+					flycast::closedir(dirs.back());
+					dirs.pop_back();
+					pathnames.pop_back();
+					continue;
+				}
+				currentItem.name = direntry->d_name;
+				if (currentItem.name == "." || currentItem.name == "..")
+					continue;
+				std::string childPath = pathnames.back() + "/" + currentItem.name;
+				bool isDir = false;
+#ifndef _WIN32
+				if (entry->d_type == DT_DIR)
+					isDir = true;
+				else if (entry->d_type == DT_UNKNOWN || entry->d_type == DT_LNK)
+#endif
+				{
+					struct stat st;
+					if (flycast::stat(childPath.c_str(), &st) != 0)
+						continue;
+					if (S_ISDIR(st.st_mode))
+						isDir = true;
+				}
+				if (!isDir)
+				{
+					currentItem.parentPath = pathnames.back();
+					break;
+				}
+
+				DIR *childDir = flycast::opendir(childPath.c_str());
+				if (childDir == nullptr)
+				{
+					INFO_LOG(COMMON, "Cannot read directory '%s'", childPath.c_str());
+				}
+				else
+				{
+					dirs.push_back(childDir);
+					pathnames.push_back(childPath);
+				}
+			}
+		}
+
+		std::vector<DIR *> dirs;
+		std::vector<std::string> pathnames;
+		dirent *direntry = nullptr;
+		item currentItem;
+
+		friend class DirectoryTree;
+	};
+
+	DirectoryTree(const std::string& root) : root(root) {
+	}
+
+	iterator begin()
+	{
+		DIR *dir = flycast::opendir(root.c_str());
+		if (dir == nullptr)
+			INFO_LOG(COMMON, "Cannot read directory '%s'", root.c_str());
+
+		return iterator(dir, root);
+	}
+	iterator end()
+	{
+		return iterator(nullptr, root);
+	}
+
+private:
+	const std::string& root;
+};
diff --git a/core/rend/CustomTexture.cpp b/core/rend/CustomTexture.cpp
index 8109b8d00..e782e99ec 100644
--- a/core/rend/CustomTexture.cpp
+++ b/core/rend/CustomTexture.cpp
@@ -20,10 +20,7 @@
 #include "cfg/cfg.h"
 #include "oslib/directory.h"
 
-#include <algorithm>
-#include <dirent.h>
 #include <sstream>
-#include <sys/stat.h>
 #define STB_IMAGE_IMPLEMENTATION
 #define STBI_ONLY_JPEG
 #define STBI_ONLY_PNG
@@ -41,33 +38,33 @@ void CustomTexture::LoaderThread()
 		BaseTextureCacheData *texture;
 		
 		do {
-			texture = NULL;
-
-			work_queue_mutex.lock();
-			if (!work_queue.empty())
+			texture = nullptr;
 			{
-				texture = work_queue.back();
-				work_queue.pop_back();
+				std::unique_lock<std::mutex> lock(work_queue_mutex);
+				if (!work_queue.empty())
+				{
+					texture = work_queue.back();
+					work_queue.pop_back();
+				}
 			}
-			work_queue_mutex.unlock();
 			
-			if (texture != NULL)
+			if (texture != nullptr)
 			{
 				texture->ComputeHash();
-				if (texture->custom_image_data != NULL)
+				if (texture->custom_image_data != nullptr)
 				{
 					free(texture->custom_image_data);
-					texture->custom_image_data = NULL;
+					texture->custom_image_data = nullptr;
 				}
 				if (!texture->dirty)
 				{
 					int width, height;
 					u8 *image_data = LoadCustomTexture(texture->texture_hash, width, height);
-					if (image_data == NULL)
+					if (image_data == nullptr)
 					{
 						image_data = LoadCustomTexture(texture->old_texture_hash, width, height);
 					}
-					if (image_data != NULL)
+					if (image_data != nullptr)
 					{
 						texture->custom_width = width;
 						texture->custom_height = height;
@@ -77,7 +74,7 @@ void CustomTexture::LoaderThread()
 				texture->custom_load_in_progress--;
 			}
 
-		} while (texture != NULL);
+		} while (texture != nullptr);
 		
 		wakeup_thread.Wait();
 	}
@@ -105,8 +102,8 @@ bool CustomTexture::Init()
 		{
 			textures_path = get_readonly_data_path("textures/" + game_id) + "/";
 
-			DIR *dir = opendir(textures_path.c_str());
-			if (dir != NULL)
+			DIR *dir = flycast::opendir(textures_path.c_str());
+			if (dir != nullptr)
 			{
 				INFO_LOG(RENDERER, "Found custom textures directory: %s", textures_path.c_str());
 				custom_textures_available = true;
@@ -123,9 +120,10 @@ void CustomTexture::Terminate()
 	if (initialized)
 	{
 		initialized = false;
-		work_queue_mutex.lock();
-		work_queue.clear();
-		work_queue_mutex.unlock();
+		{
+			std::unique_lock<std::mutex> lock(work_queue_mutex);
+			work_queue.clear();
+		}
 		wakeup_thread.Set();
 		loader_thread.WaitToEnd();
 		texture_map.clear();
@@ -154,9 +152,10 @@ void CustomTexture::LoadCustomTextureAsync(BaseTextureCacheData *texture_data)
 		return;
 
 	texture_data->custom_load_in_progress++;
-	work_queue_mutex.lock();
-	work_queue.insert(work_queue.begin(), texture_data);
-	work_queue_mutex.unlock();
+	{
+		std::unique_lock<std::mutex> lock(work_queue_mutex);
+		work_queue.insert(work_queue.begin(), texture_data);
+	}
 	wakeup_thread.Set();
 }
 
@@ -238,35 +237,14 @@ void CustomTexture::DumpTexture(u32 hash, int w, int h, TextureType textype, voi
 void CustomTexture::LoadMap()
 {
 	texture_map.clear();
-	DIR *dir = flycast::opendir(textures_path.c_str());
-	if (dir == nullptr)
-		return;
-	while (true)
+	DirectoryTree tree(textures_path);
+	for (const DirectoryTree::item& item : tree)
 	{
-		struct dirent *entry = flycast::readdir(dir);
-		if (entry == nullptr)
-			break;
-		std::string name(entry->d_name);
-		if (name == "." || name == "..")
-			continue;
-		std::string child_path = textures_path + name;
-#ifndef _WIN32
-		if (entry->d_type == DT_DIR)
-			continue;
-		if (entry->d_type == DT_UNKNOWN || entry->d_type == DT_LNK)
-#endif
-		{
-			struct stat st;
-			if (flycast::stat(child_path.c_str(), &st) != 0)
-				continue;
-			if (S_ISDIR(st.st_mode))
-				continue;
-		}
-		std::string extension = get_file_extension(name);
+		std::string extension = get_file_extension(item.name);
 		if (extension != "jpg" && extension != "jpeg" && extension != "png")
 			continue;
-		std::string::size_type dotpos = name.find_last_of('.');
-		std::string basename = name.substr(0, dotpos);
+		std::string::size_type dotpos = item.name.find_last_of('.');
+		std::string basename = item.name.substr(0, dotpos);
 		char *endptr;
 		u32 hash = (u32)strtoll(basename.c_str(), &endptr, 16);
 		if (endptr - basename.c_str() < (ptrdiff_t)basename.length())
@@ -274,8 +252,7 @@ void CustomTexture::LoadMap()
 			INFO_LOG(RENDERER, "Invalid hash %s", basename.c_str());
 			continue;
 		}
-		texture_map[hash] = child_path;
+		texture_map[hash] = item.parentPath + "/" + item.name;
 	}
-	flycast::closedir(dir);
 	custom_textures_available = !texture_map.empty();
 }
diff --git a/core/rend/CustomTexture.h b/core/rend/CustomTexture.h
index e27f49e31..c005e78c7 100644
--- a/core/rend/CustomTexture.h
+++ b/core/rend/CustomTexture.h
@@ -24,6 +24,7 @@
 #include <string>
 #include <vector>
 #include <map>
+#include <mutex>
 
 class CustomTexture {
 public:
diff --git a/core/rend/game_scanner.h b/core/rend/game_scanner.h
index 93ca51e82..c806c7aa3 100644
--- a/core/rend/game_scanner.h
+++ b/core/rend/game_scanner.h
@@ -55,7 +55,7 @@ class GameScanner
 
 	void add_game_directory(const std::string& path)
 	{
-		//printf("Exploring %s\n", path.c_str());
+		// FIXME this won't work anymore
         if (game_list.size() == 0)
         {
             ++empty_folders_scanned;
@@ -67,63 +67,36 @@ class GameScanner
             content_path_looks_incorrect = false;
         }
         
-		DIR *dir = flycast::opendir(path.c_str());
-		if (dir == NULL)
-			return;
-		while (running)
-		{
-			dirent *entry = flycast::readdir(dir);
-			if (entry == NULL)
-				break;
-			std::string name(entry->d_name);
-			if (name == "." || name == "..")
+        DirectoryTree tree(path);
+        for (const DirectoryTree::item& item : tree)
+        {
+        	std::string name(item.name);
+			std::string child_path = item.parentPath + "/" + name;
+
+			std::string extension = get_file_extension(name);
+			if (extension == "zip" || extension == "7z")
+			{
+				std::string basename = get_file_basename(name);
+				string_tolower(basename);
+				auto it = arcade_games.find(basename);
+				if (it == arcade_games.end())
+					continue;
+				name = name + " (" + std::string(it->second->description) + ")";
+			}
+			else if (extension == "chd" || extension == "gdi")
+			{
+				// Hide arcade gdroms
+				std::string basename = get_file_basename(name);
+				string_tolower(basename);
+				if (arcade_gdroms.count(basename) != 0)
+					continue;
+			}
+			else if ((settings.dreamcast.HideLegacyNaomiRoms
+							|| (extension != "bin" && extension != "lst" && extension != "dat"))
+					&& extension != "cdi" && extension != "cue")
 				continue;
-			std::string child_path = path + "/" + name;
-			bool is_dir = false;
-#ifndef _WIN32
-			if (entry->d_type == DT_DIR)
-				is_dir = true;
-			if (entry->d_type == DT_UNKNOWN || entry->d_type == DT_LNK)
-#endif
-			{
-				struct stat st;
-				if (flycast::stat(child_path.c_str(), &st) != 0)
-					continue;
-				if (S_ISDIR(st.st_mode))
-					is_dir = true;
-			}
-			if (is_dir)
-			{
-				add_game_directory(child_path);
-			}
-			else
-			{
-				std::string extension = get_file_extension(name);
-				if (extension == "zip" || extension == "7z")
-				{
-					std::string basename = get_file_basename(name);
-					string_tolower(basename);
-					auto it = arcade_games.find(basename);
-					if (it == arcade_games.end())
-						continue;
-					name = name + " (" + std::string(it->second->description) + ")";
-				}
-				else if (extension == "chd" || extension == "gdi")
-				{
-					// Hide arcade gdroms
-					std::string basename = get_file_basename(name);
-					string_tolower(basename);
-					if (arcade_gdroms.count(basename) != 0)
-						continue;
-				}
-				else if ((settings.dreamcast.HideLegacyNaomiRoms
-								|| (extension != "bin" && extension != "lst" && extension != "dat"))
-						&& extension != "cdi" && extension != "cue")
-					continue;
-				insert_game(GameMedia{ name, child_path });
-			}
+			insert_game(GameMedia{ name, child_path });
 		}
-		flycast::closedir(dir);
 	}
 
 public:
diff --git a/core/rend/gui_util.cpp b/core/rend/gui_util.cpp
index a5b5d3442..c161772ea 100644
--- a/core/rend/gui_util.cpp
+++ b/core/rend/gui_util.cpp
@@ -111,7 +111,7 @@ void select_directory_popup(const char *prompt, float scaling, StringCallback ca
 			if (select_current_directory == PSEUDO_ROOT)
 			{
 				error_message = "Storage Locations";
-				const char *home = getenv("REICAST_HOME");
+				const char *home = nowide::getenv("REICAST_HOME");
 				while (home != NULL)
 				{
 					const char *pcolon = strchr(home, ':');