diff --git a/src/common/apple.h b/src/common/apple.h
index a2edcda6b..207f75663 100644
--- a/src/common/apple.h
+++ b/src/common/apple.h
@@ -38,10 +38,10 @@ enum UserDirectory
 	USER_DIRECTORY_DOCUMENTS,
 	USER_DIRECTORY_DESKTOP,
 	USER_DIRECTORY_CACHES,
+	USER_DIRECTORY_TEMP,
 };
 
 std::string getUserDirectory(UserDirectory dir);
-
 std::string getExecutablePath();
 
 } // apple
diff --git a/src/common/apple.mm b/src/common/apple.mm
index 9b27152dc..dcffa4d76 100644
--- a/src/common/apple.mm
+++ b/src/common/apple.mm
@@ -52,6 +52,9 @@ std::string getUserDirectory(UserDirectory dir)
 		case USER_DIRECTORY_CACHES:
 			nsdir = NSCachesDirectory;
 			break;
+		case USER_DIRECTORY_TEMP:
+			nsdir = NSItemReplacementDirectory;
+			break;
 		}
 
 		NSArray<NSURL *> *dirs = [[NSFileManager defaultManager] URLsForDirectory:nsdir inDomains:NSUserDomainMask];
diff --git a/src/modules/filesystem/Filesystem.cpp b/src/modules/filesystem/Filesystem.cpp
index 56f028ae9..a44703308 100644
--- a/src/modules/filesystem/Filesystem.cpp
+++ b/src/modules/filesystem/Filesystem.cpp
@@ -28,8 +28,10 @@
 
 #if defined(LOVE_MACOS) || defined(LOVE_IOS)
 #include "common/apple.h"
+#include <unistd.h>
 #elif defined(LOVE_WINDOWS)
 #include <windows.h>
+#include <fileapi.h>
 #include "common/utf8.h"
 #elif defined(LOVE_LINUX)
 #include <unistd.h>
@@ -68,6 +70,14 @@ FileData *Filesystem::newFileData(const void *data, size_t size, const char *fil
 }
 
 bool Filesystem::isRealDirectory(const std::string &path) const
+{
+	FileType ftype = FILETYPE_MAX_ENUM;
+	if (!getRealPathType(path, ftype))
+		return false;
+	return ftype == FILETYPE_DIRECTORY;
+}
+
+bool Filesystem::getRealPathType(const std::string &path, FileType &ftype) const
 {
 #ifdef LOVE_WINDOWS
 	// make sure non-ASCII paths work.
@@ -77,15 +87,85 @@ bool Filesystem::isRealDirectory(const std::string &path) const
 	if (_wstat(wpath.c_str(), &buf) != 0)
 		return false;
 
-	return (buf.st_mode & _S_IFDIR) == _S_IFDIR;
+	if ((buf.st_mode & _S_IFREG) == _S_IFREG)
+		ftype = FILETYPE_FILE;
+	else if ((buf.st_mode & _S_IFDIR) == _S_IFDIR)
+		ftype = FILETYPE_DIRECTORY;
+	else if ((buf.st_mode & _S_IFLNK) == _S_IFLNK)
+		ftype = FILETYPE_SYMLINK;
+	else
+		ftype = FILETYPE_OTHER;
 #else
 	// Assume POSIX support...
 	struct stat buf;
 	if (stat(path.c_str(), &buf) != 0)
 		return false;
 
-	return S_ISDIR(buf.st_mode) != 0;
+	if (S_ISREG(buf.st_mode))
+		ftype = FILETYPE_FILE;
+	else if (S_ISDIR(buf.st_mode))
+		ftype = FILETYPE_DIRECTORY;
+	else if (S_ISLNK(buf.st_mode))
+		ftype = FILETYPE_SYMLINK;
+	else
+		ftype = FILETYPE_OTHER;
 #endif
+
+	return true;
+}
+
+static bool getContainingDirectory(const std::string &path, std::string &newpath)
+{
+	size_t index = path.find_last_of("/\\");
+
+	if (index == std::string::npos)
+		return false;
+
+	newpath = path.substr(0, index);
+
+	// Bail if the root has been stripped out.
+	return newpath.find("/\\") != std::string::npos;
+}
+
+static bool createDirectoryRaw(const std::string &path)
+{
+#ifdef LOVE_WINDOWS
+	std::wstring wpath = to_widestr(path);
+	return CreateDirectoryW(wpath, nullptr) != 0;
+#else
+	return mkdir(path.c_str(), S_IRWXU) == 0;
+#endif
+}
+
+bool Filesystem::createRealDirectory(const std::string &path)
+{
+	FileType ftype = FILETYPE_MAX_ENUM;
+	if (getRealPathType(path, ftype))
+		return ftype == FILETYPE_DIRECTORY;
+
+	std::vector<std::string> createpaths = {path};
+
+	// Find the deepest subdirectory in the given path that actually exists.
+	while (true)
+	{
+		std::string subpath;
+		if (!getContainingDirectory(createpaths[0], subpath))
+			break;
+
+		if (isRealDirectory(subpath))
+			break;
+
+		createpaths.insert(createpaths.begin(), subpath);
+	}
+
+	// Try to create missing subdirectories starting from that existing one.
+	for (const std::string &p : createpaths)
+	{
+		if (!createDirectoryRaw(p))
+			return false;
+	}
+
+	return true;
 }
 
 std::string Filesystem::getExecutablePath() const
@@ -127,9 +207,8 @@ STRINGMAP_CLASS_END(Filesystem, Filesystem::FileType, Filesystem::FILETYPE_MAX_E
 
 STRINGMAP_CLASS_BEGIN(Filesystem, Filesystem::CommonPath, Filesystem::COMMONPATH_MAX_ENUM, commonPath)
 {
-	{ "appidentity",   Filesystem::COMMONPATH_APP_IDENTITY   },
+	{ "appsavedir",    Filesystem::COMMONPATH_APP_SAVEDIR    },
 	{ "appdocuments",  Filesystem::COMMONPATH_APP_DOCUMENTS  },
-	{ "apptemp",       Filesystem::COMMONPATH_APP_TEMP       },
 	{ "userhome",      Filesystem::COMMONPATH_USER_HOME      },
 	{ "userappdata",   Filesystem::COMMONPATH_USER_APPDATA   },
 	{ "userdesktop",   Filesystem::COMMONPATH_USER_DESKTOP   },
diff --git a/src/modules/filesystem/Filesystem.h b/src/modules/filesystem/Filesystem.h
index e2c8c3d50..e58c9ad13 100644
--- a/src/modules/filesystem/Filesystem.h
+++ b/src/modules/filesystem/Filesystem.h
@@ -73,9 +73,8 @@ public:
 
 	enum CommonPath
 	{
-		COMMONPATH_APP_IDENTITY,
+		COMMONPATH_APP_SAVEDIR,
 		COMMONPATH_APP_DOCUMENTS,
-		COMMONPATH_APP_TEMP,
 		COMMONPATH_USER_HOME,
 		COMMONPATH_USER_APPDATA,
 		COMMONPATH_USER_DESKTOP,
@@ -163,6 +162,7 @@ public:
 	virtual bool unmount(const char *archive) = 0;
 	virtual bool unmount(Data *data) = 0;
 	virtual bool unmount(CommonPath path) = 0;
+	virtual bool unmountFullPath(const char *fullpath) = 0;
 
 	/**
 	 * Creates a new file.
@@ -177,6 +177,9 @@ public:
 	 **/
 	virtual FileData *newFileData(const void *data, size_t size, const char *filename) const;
 
+	/**
+	 * Gets the full path for the given common path.
+	 */
 	virtual std::string getFullCommonPath(CommonPath path) = 0;
 
 	/**
@@ -199,7 +202,7 @@ public:
 	/**
 	 * Gets the full path of the save folder.
 	 **/
-	virtual const char *getSaveDirectory() = 0;
+	virtual std::string getSaveDirectory() = 0;
 
 	/**
 	 * Gets the full path to the directory containing the game source.
@@ -285,6 +288,11 @@ public:
 	 **/
 	virtual bool isRealDirectory(const std::string &path) const;
 
+	/**
+	 * Recursively creates a directory at the given full OS-dependent path.
+	 **/
+	virtual bool createRealDirectory(const std::string &path);
+
 	/**
 	 * Gets the full platform-dependent path to the executable.
 	 **/
@@ -296,6 +304,8 @@ public:
 
 private:
 
+	bool getRealPathType(const std::string &path, FileType &ftype) const;
+
 	// Should we save external or internal for Android
 	bool useExternal;
 
diff --git a/src/modules/filesystem/physfs/File.cpp b/src/modules/filesystem/physfs/File.cpp
index 451be301f..c20626f21 100644
--- a/src/modules/filesystem/physfs/File.cpp
+++ b/src/modules/filesystem/physfs/File.cpp
@@ -69,14 +69,13 @@ bool File::open(Mode mode)
 		throw love::Exception("Could not open file %s. Does not exist.", filename.c_str());
 
 	// Check whether the write directory is set.
-	if ((mode == MODE_APPEND || mode == MODE_WRITE) && (PHYSFS_getWriteDir() == nullptr) && !setupWriteDirectory())
+	if ((mode == MODE_APPEND || mode == MODE_WRITE) && !setupWriteDirectory())
 		throw love::Exception("Could not set write directory.");
 
 	// File already open?
 	if (file != nullptr)
 		return false;
 
-	PHYSFS_getLastErrorCode();
 	PHYSFS_File *handle = nullptr;
 
 	switch (mode)
diff --git a/src/modules/filesystem/physfs/Filesystem.cpp b/src/modules/filesystem/physfs/Filesystem.cpp
index 7833e051e..b329344ca 100644
--- a/src/modules/filesystem/physfs/Filesystem.cpp
+++ b/src/modules/filesystem/physfs/Filesystem.cpp
@@ -71,25 +71,6 @@ namespace filesystem
 namespace physfs
 {
 
-static size_t getDriveDelim(const std::string &input)
-{
-	for (size_t i = 0; i < input.size(); ++i)
-		if (input[i] == '/' || input[i] == '\\')
-			return i;
-	// Something's horribly wrong
-	return 0;
-}
-
-static std::string getDriveRoot(const std::string &input)
-{
-	return input.substr(0, getDriveDelim(input)+1);
-}
-
-static std::string skipDriveRoot(const std::string &input)
-{
-	return input.substr(getDriveDelim(input)+1);
-}
-
 static std::string normalize(const std::string &input)
 {
 	std::stringstream out;
@@ -105,13 +86,18 @@ static std::string normalize(const std::string &input)
 	return out.str();
 }
 
+static const Filesystem::CommonPath appCommonPaths[] =
+{
+	Filesystem::COMMONPATH_APP_SAVEDIR,
+	Filesystem::COMMONPATH_APP_DOCUMENTS
+};
+
 static bool isAppCommonPath(Filesystem::CommonPath path)
 {
 	switch (path)
 	{
-	case Filesystem::COMMONPATH_APP_IDENTITY:
+	case Filesystem::COMMONPATH_APP_SAVEDIR:
 	case Filesystem::COMMONPATH_APP_DOCUMENTS:
-	case Filesystem::COMMONPATH_APP_TEMP:
 		return true;
 	default:
 		return false;
@@ -119,8 +105,12 @@ static bool isAppCommonPath(Filesystem::CommonPath path)
 }
 
 Filesystem::Filesystem()
-	: fused(false)
+	: appendIdentityToPath(false)
+	, fused(false)
 	, fusedSet(false)
+	, fullPaths()
+	, commonPathMountInfo()
+	, saveDirectoryNeedsMounting(false)
 {
 	requirePath = {"?.lua", "?/init.lua"};
 	cRequirePath = {"??"};
@@ -166,65 +156,65 @@ bool Filesystem::setIdentity(const char *ident, bool appendToPath)
 	if (!PHYSFS_isInit())
 		return false;
 
-	std::string old_save_path = save_path_full;
+	if (ident == nullptr || strlen(ident) == 0)
+		return false;
 
-	// Store the save directory.
-	save_identity = std::string(ident);
+	// Validate whether re-mounting will work.
+	for (CommonPath p : appCommonPaths)
+	{
+		if (!commonPathMountInfo[p].mounted)
+			continue;
 
-	// Generate the relative path to the game save folder.
-	if (fused)
-		save_path_relative = std::string(LOVE_APPDATA_PREFIX) + save_identity;
-	else
-		save_path_relative = std::string(LOVE_APPDATA_PREFIX LOVE_APPDATA_FOLDER LOVE_PATH_SEPARATOR) + save_identity;
+		// If a file is still open, unmount will fail.
+		std::string fullPath = getFullCommonPath(p);
+		if (!fullPath.empty() && !PHYSFS_canUnmount(fullPath.c_str()))
+			return false;
+	}
 
-	// Generate the full path to the game save folder.
-	save_path_full = std::string(getAppdataDirectory()) + std::string(LOVE_PATH_SEPARATOR) + save_path_relative;
-	save_path_full = normalize(save_path_full);	
-	
-#ifdef LOVE_ANDROID
-	if (save_identity == "")
-		save_identity = "unnamed";
+	bool oldMountedCommonPaths[COMMONPATH_MAX_ENUM] = {false};
 
-	std::string storage_path;
-	if (isAndroidSaveExternal())
-		storage_path = SDL_AndroidGetExternalStoragePath();
-	else
-		storage_path = SDL_AndroidGetInternalStoragePath();
+	// We don't want old save paths to accumulate when we set a new identity.
+	for (CommonPath p : appCommonPaths)
+	{
+		oldMountedCommonPaths[p] = commonPathMountInfo[p].mounted;
+		if (commonPathMountInfo[p].mounted)
+			unmount(p);
+	}
 
-	std::string save_directory = storage_path + "/save";
+	// These will be re-populated by getFullCommonPath.
+	for (CommonPath p : appCommonPaths)
+		fullPaths[p].clear();
 
-	save_path_full = storage_path + std::string("/save/") + save_identity;
+	// Store the save directory. getFullCommonPath(COMMONPATH_APP_*) uses this.
+	saveIdentity = std::string(ident);
+	appendIdentityToPath = appendToPath;
 
-	if (!love::android::directoryExists(save_path_full.c_str()) &&
-			!love::android::mkdir(save_path_full.c_str()))
-		SDL_Log("Error: Could not create save directory %s!", save_path_full.c_str());
-#endif
+	// Try to mount as readwrite without creating missing directories in the
+	// path hierarchy. If this fails, setupWriteDirectory will attempt to create
+	// them and try again.
+	// This is done so the save directory is only created on-demand.
+	if (!mountCommonPathInternal(COMMONPATH_APP_SAVEDIR, nullptr, MOUNT_PERMISSIONS_READWRITE, appendToPath, false))
+		saveDirectoryNeedsMounting = true;
 
-	// We now have something like:
-	// save_identity: game
-	// save_path_relative: ./LOVE/game
-	// save_path_full: C:\Documents and Settings\user\Application Data/LOVE/game
-
-	// We don't want old read-only save paths to accumulate when we set a new
-	// identity.
-	if (!old_save_path.empty())
-		PHYSFS_unmount(old_save_path.c_str());
-
-	// Try to add the save directory to the search path.
-	// (No error on fail, it means that the path doesn't exist).
-	PHYSFS_mount(save_path_full.c_str(), nullptr, appendToPath);
-
-	// HACK: This forces setupWriteDirectory to be called the next time a file
-	// is opened for writing - otherwise it won't be called at all if it was
-	// already called at least once before.
-	PHYSFS_setWriteDir(nullptr);
+	// Mount any other app common paths with directory creation immediately
+	// instead of on-demand, since to get to this point they would have to be
+	// explicitly mounted already beforehand.
+	for (CommonPath p : appCommonPaths)
+	{
+		if (oldMountedCommonPaths[p] && p != COMMONPATH_APP_SAVEDIR)
+		{
+			// TODO: error handling?
+			auto info = commonPathMountInfo[p];
+			mountCommonPathInternal(p, info.mountPoint.c_str(), info.permissions, appendToPath, true);
+		}
+	}
 
 	return true;
 }
 
 const char *Filesystem::getIdentity() const
 {
-	return save_identity.c_str();
+	return saveIdentity.c_str();
 }
 
 bool Filesystem::setSource(const char *source)
@@ -233,7 +223,7 @@ bool Filesystem::setSource(const char *source)
 		return false;
 
 	// Check whether directory is already set.
-	if (!game_source.empty())
+	if (!gameSource.empty())
 		return false;
 
 	std::string new_search_path = source;
@@ -275,14 +265,14 @@ bool Filesystem::setSource(const char *source)
 #endif
 
 	// Save the game source.
-	game_source = new_search_path;
+	gameSource = new_search_path;
 
 	return true;
 }
 
 const char *Filesystem::getSource() const
 {
-	return game_source.c_str();
+	return gameSource.c_str();
 }
 
 bool Filesystem::setupWriteDirectory()
@@ -290,54 +280,19 @@ bool Filesystem::setupWriteDirectory()
 	if (!PHYSFS_isInit())
 		return false;
 
-	// These must all be set.
-	if (save_identity.empty() || save_path_full.empty() || save_path_relative.empty())
+	if (!saveDirectoryNeedsMounting)
+		return true;
+
+	if (saveIdentity.empty())
 		return false;
 
-	// We need to make sure the write directory is created. To do that, we also
-	// need to make sure all its parent directories are also created.
-	std::string temp_writedir = getDriveRoot(save_path_full);
-	std::string temp_createdir = skipDriveRoot(save_path_full);
-
-	// On some sandboxed platforms, physfs will break when its write directory
-	// is the root of the drive and it tries to create a folder (even if the
-	// folder's path is in a writable location.) If the user's home folder is
-	// in the save path, we'll try starting from there instead.
-	if (save_path_full.find(getUserDirectory()) == 0)
-	{
-		temp_writedir = getUserDirectory();
-		temp_createdir = save_path_full.substr(getUserDirectory().length());
-
-		// Strip leading '/' characters from the path we want to create.
-		size_t startpos = temp_createdir.find_first_not_of('/');
-		if (startpos != std::string::npos)
-			temp_createdir = temp_createdir.substr(startpos);
-	}
-
-	// Set either '/' or the user's home as a writable directory.
-	// (We must create the save folder before mounting it).
-	if (!PHYSFS_setWriteDir(temp_writedir.c_str()))
+	// Only the save directory is mounted on-demand if it doesn't exist yet.
+	// Other app common paths are immediately re-mounted in setIdentity.
+	bool createdir = true;
+	if (!mountCommonPathInternal(COMMONPATH_APP_SAVEDIR, nullptr, MOUNT_PERMISSIONS_READWRITE, appendIdentityToPath, createdir))
 		return false;
 
-	// Create the save folder. (We're now "at" either '/' or the user's home).
-	if (!createDirectory(temp_createdir.c_str()))
-	{
-		// Clear the write directory in case of error.
-		PHYSFS_setWriteDir(nullptr);
-		return false;
-	}
-
-	// Set the final write directory.
-	if (!PHYSFS_setWriteDir(save_path_full.c_str()))
-		return false;
-
-	// Add the directory. (Will not be readded if already present).
-	if (!PHYSFS_mount(save_path_full.c_str(), nullptr, 0))
-	{
-		PHYSFS_setWriteDir(nullptr); // Clear the write directory in case of error.
-		return false;
-	}
-
+	saveDirectoryNeedsMounting = false;
 	return true;
 }
 
@@ -374,7 +329,7 @@ bool Filesystem::mount(const char *archive, const char *mountpoint, bool appendT
 
 		// Always disallow mounting of files inside the game source, since it
 		// won't work anyway if the game source is a zipped .love file.
-		if (realPath.find(game_source) == 0)
+		if (realPath.find(gameSource) == 0)
 			return false;
 
 		realPath += LOVE_PATH_SEPARATOR;
@@ -386,30 +341,40 @@ bool Filesystem::mount(const char *archive, const char *mountpoint, bool appendT
 
 bool Filesystem::mountFullPath(const char *archive, const char *mountpoint, MountPermissions permissions, bool appendToPath)
 {
-	if (!PHYSFS_isInit() || !archive || !mountpoint)
+	if (!PHYSFS_isInit() || !archive)
 		return false;
 
-	if (permissions == MOUNT_PERMISSIONS_READWRITE && strlen(mountpoint) == 0)
-		return false;
+	if (permissions == MOUNT_PERMISSIONS_READWRITE)
+		return PHYSFS_mountRW(archive, mountpoint, appendToPath) != 0;
 
-	// TODO: readwrite mount
 	return PHYSFS_mount(archive, mountpoint, appendToPath) != 0;
 }
 
-bool Filesystem::mountCommonPath(CommonPath path, const char *mountpoint, MountPermissions permissions, bool appendToPath)
+bool Filesystem::mountCommonPathInternal(CommonPath path, const char *mountpoint, MountPermissions permissions, bool appendToPath, bool createDir)
 {
 	std::string fullpath = getFullCommonPath(path);
 	if (fullpath.empty())
 		return false;
 
-	bool success = mountFullPath(fullpath.c_str(), mountpoint, permissions, appendToPath);
-
-	if (!success && isAppCommonPath(path))
+	if (createDir && isAppCommonPath(path) && !isRealDirectory(fullpath))
 	{
-		
+		if (!createRealDirectory(fullpath))
+			return false;
 	}
 
-	return success;
+	if (mountFullPath(fullpath.c_str(), mountpoint, permissions, appendToPath))
+	{
+		std::string mp = mountpoint != nullptr ? mountpoint : "/";
+		commonPathMountInfo[path] = {true, mp, permissions};
+		return true;
+	}
+
+	return false;
+}
+
+bool Filesystem::mountCommonPath(CommonPath path, const char *mountpoint, MountPermissions permissions, bool appendToPath)
+{
+	return mountCommonPathInternal(path, mountpoint, permissions, appendToPath, true);
 }
 
 bool Filesystem::mount(Data *data, const char *archivename, const char *mountpoint, bool appendToPath)
@@ -439,8 +404,13 @@ bool Filesystem::unmount(const char *archive)
 		return true;
 	}
 
-	if (PHYSFS_getRealDir(archive) != nullptr)
-		return PHYSFS_unmount(archive) != 0;
+	auto it = std::find(allowedMountPaths.begin(), allowedMountPaths.end(), archive);
+	if (it != allowedMountPaths.end())
+		return unmountFullPath(archive);
+
+	std::string sourceBase = getSourceBaseDirectory();
+	if (isFused() && sourceBase.compare(archive) == 0)
+		return unmountFullPath(archive);
 
 	if (strlen(archive) == 0 || strstr(archive, "..") || strcmp(archive, "/") == 0)
 		return false;
@@ -459,13 +429,25 @@ bool Filesystem::unmount(const char *archive)
 	return PHYSFS_unmount(realPath.c_str()) != 0;
 }
 
+bool Filesystem::unmountFullPath(const char *fullpath)
+{
+	if (!PHYSFS_isInit() || !fullpath)
+		return false;
+
+	return PHYSFS_unmount(fullpath) != 0;
+}
+
 bool Filesystem::unmount(CommonPath path)
 {
 	std::string fullpath = getFullCommonPath(path);
-	if (fullpath.empty())
-		return false;
 
-	return unmount(fullpath.c_str());
+	if (!fullpath.empty() && unmountFullPath(fullpath.c_str()))
+	{
+		commonPathMountInfo[path].mounted = false;
+		return true;
+	}
+
+	return false;
 }
 
 bool Filesystem::unmount(Data *data)
@@ -489,34 +471,60 @@ love::filesystem::File *Filesystem::newFile(const char *filename) const
 
 std::string Filesystem::getFullCommonPath(CommonPath path)
 {
-	if (!fullCommonPaths[path].empty())
-		return fullCommonPaths[path];
+	if (!fullPaths[path].empty())
+		return fullPaths[path];
 
-	if (path == COMMONPATH_APP_IDENTITY || path == COMMONPATH_APP_DOCUMENTS || path == COMMONPATH_APP_TEMP)
+	if (isAppCommonPath(path))
 	{
-		
+		if (saveIdentity.empty())
+			return fullPaths[path];
+
+		std::string rootpath;
+		switch (path)
+		{
+		case COMMONPATH_APP_SAVEDIR:
+			rootpath = getFullCommonPath(COMMONPATH_USER_APPDATA);
+			break;
+		case COMMONPATH_APP_DOCUMENTS:
+			rootpath = getFullCommonPath(COMMONPATH_USER_DOCUMENTS);
+			break;
+		default:
+			break;
+		}
+
+		if (rootpath.empty())
+			return fullPaths[path];
+
+		std::string suffix;
+		if (isFused())
+			suffix = std::string(LOVE_PATH_SEPARATOR) + saveIdentity;
+		else
+			suffix = std::string(LOVE_PATH_SEPARATOR LOVE_APPDATA_FOLDER LOVE_PATH_SEPARATOR) + saveIdentity;
+
+		fullPaths[path] = normalize(rootpath + suffix);
+
+		return fullPaths[path];
 	}
 
 #if defined(LOVE_MACOS) || defined(LOVE_IOS)
 
 	switch (path)
 	{
-	case COMMONPATH_APP_IDENTITY:
+	case COMMONPATH_APP_SAVEDIR:
 	case COMMONPATH_APP_DOCUMENTS:
-	case COMMONPATH_APP_TEMP:
 		// Handled above.
 		break;
 	case COMMONPATH_USER_HOME:
-		fullCommonPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_HOME);
+		fullPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_HOME);
 		break;
 	case COMMONPATH_USER_APPDATA:
-		fullCommonPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_APPSUPPORT);
+		fullPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_APPSUPPORT);
 		break;
 	case COMMONPATH_USER_DESKTOP:
-		fullCommonPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_DESKTOP);
+		fullPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_DESKTOP);
 		break;
 	case COMMONPATH_USER_DOCUMENTS:
-		fullCommonPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_DOCUMENTS);
+		fullPaths[path] = apple::getUserDirectory(apple::USER_DIRECTORY_DOCUMENTS);
 		break;
 	case COMMONPATH_MAX_ENUM:
 		break;
@@ -529,9 +537,8 @@ std::string Filesystem::getFullCommonPath(CommonPath path)
 
 	switch (path)
 	{
-	case COMMONPATH_APP_IDENTITY:
+	case COMMONPATH_APP_SAVEDIR:
 	case COMMONPATH_APP_DOCUMENTS:
-	case COMMONPATH_APP_TEMP:
 		// Handled above.
 		break;
 	case COMMONPATH_USER_HOME:
@@ -552,40 +559,66 @@ std::string Filesystem::getFullCommonPath(CommonPath path)
 
 	if (SUCCEEDED(hr))
 	{
-		fullCommonPaths[path] = to_utf8(winpath);
+		fullPaths[path] = to_utf8(winpath);
 		CoTaskMemFree(winpath);
 	}
-	else
-	{
-
-	}
 
 #elif defined(LOVE_ANDROID)
 
+	std::string storagepath;
+	if (isAndroidSaveExternal())
+		storagepath = SDL_AndroidGetExternalStoragePath();
+	else
+		storagepath = SDL_AndroidGetInternalStoragePath();
+
+	switch (path)
+	{
+	case COMMONPATH_APP_SAVEDIR:
+	case COMMONPATH_APP_DOCUMENTS:
+		// Handled above.
+		break;
+	case COMMONPATH_USER_HOME:
+		fullPaths[path] = normalize(PHYSFS_getUserDir());
+		break;
+	case COMMONPATH_USER_APPDATA:
+		fullPaths[path] = normalize(storagepath + "/save/");
+		break;
+	case COMMONPATH_USER_DESKTOP:
+		// No such thing on Android?
+		break;
+	case COMMONPATH_USER_DOCUMENTS:
+		// TODO: something more idiomatic / useful?
+		fullPaths[path] = normalize(storagepath + "/Documents/");
+		break;
+	case COMMONPATH_MAX_ENUM:
+		break;
+	}
+
 #elif defined(LOVE_LINUX)
 
 	const char *xdgdir = nullptr;
 
 	switch (path)
 	{
-	case COMMONPATH_APP_IDENTITY:
+	case COMMONPATH_APP_SAVEDIR:
 	case COMMONPATH_APP_DOCUMENTS:
-	case COMMONPATH_APP_TEMP:
 		// Handled above.
 		break;
 	case COMMONPATH_USER_HOME:
-		fullCommonPaths[path] = normalize(PHYSFS_getUserDir());
+		fullPaths[path] = normalize(PHYSFS_getUserDir());
 		break;
 	case COMMONPATH_USER_APPDATA:
 		xdgdir = getenv("XDG_DATA_HOME");
 		if (!xdgdir)
-			fullCommonPaths[path] = normalize(std::string(getUserDirectory()) + "/.local/share/");
+			fullPaths[path] = normalize(std::string(getUserDirectory()) + "/.local/share/");
 		else
-			fullCommonPaths[path] = xdgdir;
+			fullPaths[path] = xdgdir;
 		break;
 	case COMMONPATH_USER_DESKTOP:
+		fullPaths[path] = normalize(std::string(getUserDirectory()) + "/Desktop/");
 		break;
 	case COMMONPATH_USER_DOCUMENTS:
+		fullPaths[path] = normalize(std::string(getUserDirectory()) + "/Documents/");
 		break;
 	case COMMONPATH_MAX_ENUM:
 		break;
@@ -593,7 +626,7 @@ std::string Filesystem::getFullCommonPath(CommonPath path)
 
 #endif
 
-	return fullCommonPaths[path];
+	return fullPaths[path];
 }
 
 const char *Filesystem::getWorkingDirectory()
@@ -621,58 +654,22 @@ const char *Filesystem::getWorkingDirectory()
 
 std::string Filesystem::getUserDirectory()
 {
-#if defined(LOVE_IOS) || defined(LOVE_MACOS)
-	// PHYSFS_getUserDir doesn't give exactly the path we want on iOS.
-	static std::string userDir = normalize(apple::getUserDirectory(apple::USER_DIRECTORY_HOME));
-#else
-	static std::string userDir = normalize(PHYSFS_getUserDir());
-#endif
-
-	return userDir;
+	return getFullCommonPath(COMMONPATH_USER_HOME);
 }
 
 std::string Filesystem::getAppdataDirectory()
 {
-	if (appdata.empty())
-	{
-#ifdef LOVE_WINDOWS_UWP
-		appdata = getUserDirectory();
-#elif defined(LOVE_WINDOWS)
-		PWSTR path = nullptr;
-		if (SUCCEEDED(SHGetKnownFolderPath(FOLDERID_RoamingAppData, 0, nullptr, &path)))
-		{
-			appdata = to_utf8(path);
-			CoTaskMemFree(path);
-		}
-		else
-		{
-			wchar_t *w_appdata = _wgetenv(L"APPDATA");
-			appdata = to_utf8(w_appdata);
-		}
-		replace_char(appdata, '\\', '/');
-#elif defined(LOVE_MACOS) || defined(LOVE_IOS)
-		appdata = normalize(apple::getUserDirectory(apple::USER_DIRECTORY_APPSUPPORT));
-#elif defined(LOVE_LINUX)
-		char *xdgdatahome = getenv("XDG_DATA_HOME");
-		if (!xdgdatahome)
-			appdata = normalize(std::string(getUserDirectory()) + "/.local/share/");
-		else
-			appdata = xdgdatahome;
-#else
-		appdata = getUserDirectory();
-#endif
-	}
-	return appdata;
+	return getFullCommonPath(COMMONPATH_USER_APPDATA);
 }
 
-const char *Filesystem::getSaveDirectory()
+std::string Filesystem::getSaveDirectory()
 {
-	return save_path_full.c_str();
+	return getFullCommonPath(COMMONPATH_APP_SAVEDIR);
 }
 
 std::string Filesystem::getSourceBaseDirectory() const
 {
-	size_t source_len = game_source.length();
+	size_t source_len = gameSource.length();
 
 	if (source_len == 0)
 		return "";
@@ -681,9 +678,9 @@ std::string Filesystem::getSourceBaseDirectory() const
 	// symbols (i.e. '..' and '.')
 #ifdef LOVE_WINDOWS
 	// In windows, delimiters can be either '/' or '\'.
-	size_t base_end_pos = game_source.find_last_of("/\\", source_len - 2);
+	size_t base_end_pos = gameSource.find_last_of("/\\", source_len - 2);
 #else
-	size_t base_end_pos = game_source.find_last_of('/', source_len - 2);
+	size_t base_end_pos = gameSource.find_last_of('/', source_len - 2);
 #endif
 
 	if (base_end_pos == std::string::npos)
@@ -693,7 +690,7 @@ std::string Filesystem::getSourceBaseDirectory() const
 	if (base_end_pos == 0)
 		base_end_pos = 1;
 
-	return game_source.substr(0, base_end_pos);
+	return gameSource.substr(0, base_end_pos);
 }
 
 std::string Filesystem::getRealDirectory(const char *filename) const
@@ -739,7 +736,7 @@ bool Filesystem::createDirectory(const char *dir)
 	if (!PHYSFS_isInit())
 		return false;
 
-	if (PHYSFS_getWriteDir() == 0 && !setupWriteDirectory())
+	if (!setupWriteDirectory())
 		return false;
 
 	if (!PHYSFS_mkdir(dir))
@@ -753,7 +750,7 @@ bool Filesystem::remove(const char *file)
 	if (!PHYSFS_isInit())
 		return false;
 
-	if (PHYSFS_getWriteDir() == 0 && !setupWriteDirectory())
+	if (!setupWriteDirectory())
 		return false;
 
 	if (!PHYSFS_delete(file))
diff --git a/src/modules/filesystem/physfs/Filesystem.h b/src/modules/filesystem/physfs/Filesystem.h
index 2ccfa9dc7..1ad915981 100644
--- a/src/modules/filesystem/physfs/Filesystem.h
+++ b/src/modules/filesystem/physfs/Filesystem.h
@@ -69,6 +69,7 @@ public:
 	bool unmount(const char *archive) override;
 	bool unmount(Data *data) override;
 	bool unmount(CommonPath path) override;
+	bool unmountFullPath(const char *fullpath) override;
 
 	love::filesystem::File *newFile(const char *filename) const override;
 
@@ -76,7 +77,7 @@ public:
 	const char *getWorkingDirectory() override;
 	std::string getUserDirectory() override;
 	std::string getAppdataDirectory() override;
-	const char *getSaveDirectory() override;
+	std::string getSaveDirectory() override;
 	std::string getSourceBaseDirectory() const override;
 
 	std::string getRealDirectory(const char *filename) const override;
@@ -103,26 +104,26 @@ public:
 
 private:
 
+	struct CommonPathMountInfo
+	{
+		bool mounted;
+		std::string mountPoint;
+		MountPermissions permissions;
+	};
+
+	bool mountCommonPathInternal(CommonPath path, const char *mountpoint, MountPermissions permissions, bool appendToPath, bool createDir);
+
 	// Contains the current working directory (UTF8).
 	std::string cwd;
 
-	// %APPDATA% on Windows.
-	std::string appdata;
-
-	// This name will be used to create the folder
-	// in the appdata/userdata folder.
-	std::string save_identity;
-
-	// Full and relative paths of the game save folder.
-	// (Relative to the %APPDATA% folder, meaning that the
-	// relative string will look something like: ./LOVE/game)
-	std::string save_path_relative, save_path_full;
+	// This name will be used to create the folder in the appdata folder.
+	std::string saveIdentity;
+	bool appendIdentityToPath;
 
 	// The full path to the source of the game.
-	std::string game_source;
+	std::string gameSource;
 
-	// Allow saving outside of the LOVE_APPDATA_FOLDER
-	// for release 'builds'
+	// Allow saving outside of the LOVE_APPDATA_FOLDER for release 'builds'
 	bool fused;
 	bool fusedSet;
 
@@ -134,7 +135,11 @@ private:
 
 	std::map<std::string, StrongRef<Data>> mountedData;
 
-	std::string fullCommonPaths[COMMONPATH_MAX_ENUM];
+	std::string fullPaths[COMMONPATH_MAX_ENUM];
+
+	CommonPathMountInfo commonPathMountInfo[COMMONPATH_MAX_ENUM];
+
+	bool saveDirectoryNeedsMounting;
 
 }; // Filesystem
 
diff --git a/src/modules/filesystem/wrap_Filesystem.cpp b/src/modules/filesystem/wrap_Filesystem.cpp
index da03f2a0f..45bf3e889 100644
--- a/src/modules/filesystem/wrap_Filesystem.cpp
+++ b/src/modules/filesystem/wrap_Filesystem.cpp
@@ -205,6 +205,13 @@ int w_unmount(lua_State *L)
 	return 1;
 }
 
+int w_unmountFullPath(lua_State *L)
+{
+	const char *fullpath = luaL_checkstring(L, 1);
+	luax_pushboolean(L, instance()->unmountFullPath(fullpath));
+	return 1;
+}
+
 int w_unmountCommonPath(lua_State *L)
 {
 	const char *commonpathstr = luaL_checkstring(L, 1);
@@ -415,7 +422,7 @@ int w_getAppdataDirectory(lua_State *L)
 
 int w_getSaveDirectory(lua_State *L)
 {
-	lua_pushstring(L, instance()->getSaveDirectory());
+	luax_pushstring(L, instance()->getSaveDirectory());
 	return 1;
 }
 
@@ -907,11 +914,12 @@ static const luaL_Reg functions[] =
 	{ "getSource", w_getSource },
 	{ "mount", w_mount },
 	{ "mountFullPath", w_mountFullPath },
-//	{ "mountCommonPath", w_mountCommonPath },
+	{ "mountCommonPath", w_mountCommonPath },
 	{ "unmount", w_unmount },
-//	{ "unmountCommonPath", w_unmountCommonPath },
+	{ "unmountFullPath", w_unmountFullPath },
+	{ "unmountCommonPath", w_unmountCommonPath },
 	{ "newFile", w_newFile },
-//	{ "getFullCommonPath", w_getFullCommonPath },
+	{ "getFullCommonPath", w_getFullCommonPath },
 	{ "getWorkingDirectory", w_getWorkingDirectory },
 	{ "getUserDirectory", w_getUserDirectory },
 	{ "getAppdataDirectory", w_getAppdataDirectory },