diff --git a/src/ntfs_io.c b/src/ntfs_io.c
index 7f57edd..4b718bb 100644
--- a/src/ntfs_io.c
+++ b/src/ntfs_io.c
@@ -154,8 +154,8 @@ static int ntfs_device_testdisk_io_stat(struct ntfs_device *dev, struct stat *bu
 	return -1;
 }
 
-static int ntfs_device_testdisk_io_ioctl(struct ntfs_device *dev, int request,
-		void *argp)
+static int ntfs_device_testdisk_io_ioctl(struct ntfs_device *dev,
+                                         unsigned long request, void *argp)
 {
 	log_warning( "ntfs_device_testdisk_io_ioctl() unimplemented\n");
 #ifdef ENOTSUP