diff --git a/include/ntapi/nt_mount.h b/include/ntapi/nt_mount.h
index 8a7258a..982a24d 100644
--- a/include/ntapi/nt_mount.h
+++ b/include/ntapi/nt_mount.h
@@ -97,24 +97,24 @@ typedef struct _nt_dos_devices_name {
 
 typedef int32_t __stdcall	ntapi_tt_get_dos_drive_device_handle(
 	__out	void **			hdevice,
-	__in	wchar16_t *		drive_letter);
+	__in	wchar16_t		drive_letter);
 
 
 typedef int32_t __stdcall	ntapi_tt_get_dos_drive_root_handle(
 	__out	void **			hroot,
-	__in	wchar16_t *		drive_letter);
+	__in	wchar16_t		drive_letter);
 
 
 typedef int32_t __stdcall	ntapi_tt_get_dos_drive_device_name(
 	__in	void *			hdevice		__optional,
-	__in	wchar16_t *		drive_letter	__optional,
+	__in	wchar16_t		drive_letter	__optional,
 	__out	nt_mount_dev_name *	buffer,
 	__in	uint32_t		buffer_size);
 
 
 typedef int32_t __stdcall	ntapi_tt_get_dos_drive_mount_points(
 	__in	void *			hdevice		__optional,
-	__in	wchar16_t *		drive_letter	__optional,
+	__in	wchar16_t		drive_letter	__optional,
 	__in	nt_mount_dev_name *	dev_name	__optional,
 	__out	void *			buffer,
 	__in	uint32_t		buffer_size);
diff --git a/src/fs/ntapi_tt_mount.c b/src/fs/ntapi_tt_mount.c
index 344f5c1..c149e53 100644
--- a/src/fs/ntapi_tt_mount.c
+++ b/src/fs/ntapi_tt_mount.c
@@ -80,7 +80,7 @@ static int32_t __stdcall __tt_connect_to_mount_point_manager(void)
 
 static int32_t __stdcall __tt_get_dos_drive_device_or_root_handle(
 	__out	void **			hdrive,
-	__in	wchar16_t *		drive_letter,
+	__in	wchar16_t		drive_letter,
 	__in	_dos_drive_handle_type	handle_type)
 {
 	#define		__common_mode	(NT_FILE_SYNCHRONOUS_IO_ALERT)
@@ -98,13 +98,10 @@ static int32_t __stdcall __tt_get_dos_drive_device_or_root_handle(
 					{'\\','?','?','\\'},
 					'_',':',0,0};
 
-	if (!hdrive || !drive_letter)
-		return NT_STATUS_INVALID_PARAMETER;
-
-	if ((*drive_letter>='A') && (*drive_letter<='Z'))
-		dos_name_buffer.dos_letter = *drive_letter;
-	else if ((*drive_letter>='a') && (*drive_letter<='z'))
-		dos_name_buffer.dos_letter = *drive_letter + 'A' - 'a';
+	if ((drive_letter>='A') && (drive_letter<='Z'))
+		dos_name_buffer.dos_letter = drive_letter;
+	else if ((drive_letter>='a') && (drive_letter<='z'))
+		dos_name_buffer.dos_letter = drive_letter + 'A' - 'a';
 	else
 		return NT_STATUS_INVALID_PARAMETER_2;
 
@@ -151,7 +148,7 @@ static int32_t __stdcall __tt_get_dos_drive_device_or_root_handle(
 
 int32_t __stdcall	__ntapi_tt_get_dos_drive_device_handle(
 	__out	void **			hdevice,
-	__in	wchar16_t *		drive_letter)
+	__in	wchar16_t		drive_letter)
 {
 	return __tt_get_dos_drive_device_or_root_handle(
 		hdevice,
@@ -162,7 +159,7 @@ int32_t __stdcall	__ntapi_tt_get_dos_drive_device_handle(
 
 int32_t __stdcall	__ntapi_tt_get_dos_drive_root_handle(
 	__out	void **			hroot,
-	__in	wchar16_t *		drive_letter)
+	__in	wchar16_t		drive_letter)
 {
 	return __tt_get_dos_drive_device_or_root_handle(
 		hroot,
@@ -174,7 +171,7 @@ int32_t __stdcall	__ntapi_tt_get_dos_drive_root_handle(
 
 int32_t __stdcall	__ntapi_tt_get_dos_drive_device_name(
 	__in	void *			hdevice		__optional,
-	__in	wchar16_t *		drive_letter	__optional,
+	__in	wchar16_t		drive_letter	__optional,
 	__out	nt_mount_dev_name *	buffer,
 	__in	uint32_t		buffer_size)
 {
@@ -203,7 +200,7 @@ int32_t __stdcall	__ntapi_tt_get_dos_drive_device_name(
 
 int32_t __stdcall	__ntapi_tt_get_dos_drive_mount_points(
 	__in	void *			hdevice		__optional,
-	__in	wchar16_t *		drive_letter	__optional,
+	__in	wchar16_t		drive_letter	__optional,
 	__in	nt_mount_dev_name *	dev_name	__optional,
 	__out	void *			buffer,
 	__in	uint32_t		buffer_size)
@@ -347,13 +344,10 @@ int32_t __stdcall	__ntapi_tt_get_dos_drive_letter_from_device(
 
 	if (!dev_name) {
 		dev_name = (nt_mount_dev_name *)&dev_name_buffer;
-		status = __ntapi_tt_get_dos_drive_device_name(
-			hdevice,
-			(wchar16_t *)0,
-			dev_name,
-			sizeof(dev_name_buffer));
 
-		if (status != NT_STATUS_SUCCESS)
+		if ((status = __ntapi_tt_get_dos_drive_device_name(
+				hdevice,0,dev_name,
+				sizeof(dev_name_buffer))))
 			return status;
 	}
 
diff --git a/src/fs/ntapi_tt_statfs.c b/src/fs/ntapi_tt_statfs.c
index bc4fe51..44450df 100644
--- a/src/fs/ntapi_tt_statfs.c
+++ b/src/fs/ntapi_tt_statfs.c
@@ -204,8 +204,7 @@ int32_t __stdcall __ntapi_tt_statfs(
 	offset   = sizeof(nt_unicode_string) + statfs->dev_name_strlen;
 
 	if ((status = __ntapi->tt_get_dos_drive_mount_points(
-			(void *)0,
-			(wchar16_t *)0,
+			(void *)0,0,
 			(nt_mount_dev_name *)wch,
 			mnt_points_buffer,
 			buffer_size - offset)))