diff --git a/fs/devfs.c b/fs/devfs.c
index 007dea9..aa44e32 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -168,7 +168,7 @@
 	return cdev_ioctl(cdev, request, buf);
 }
 
-static int devfs_truncate(struct device_d *dev, FILE *f, ulong size)
+static int devfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	struct cdev *cdev = f->priv;
 
diff --git a/fs/efi.c b/fs/efi.c
index cd4fee7..81c1ffe 100644
--- a/fs/efi.c
+++ b/fs/efi.c
@@ -305,7 +305,7 @@
 	return 0;
 }
 
-static int efifs_truncate(struct device_d *dev, FILE *f, unsigned long size)
+static int efifs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	struct efifs_file *ufile = f->priv;
 	efi_status_t efiret;
diff --git a/fs/efivarfs.c b/fs/efivarfs.c
index d261577..a911eac 100644
--- a/fs/efivarfs.c
+++ b/fs/efivarfs.c
@@ -288,7 +288,7 @@
 	return insize;
 }
 
-static int efivarfs_truncate(struct device_d *dev, FILE *f, ulong size)
+static int efivarfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	struct efivars_file *efile = f->priv;
 	efi_status_t efiret;
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 1367577..394c75f 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -177,7 +177,7 @@
 	return outsize;
 }
 
-static int fat_truncate(struct device_d *dev, FILE *f, ulong size)
+static int fat_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	FIL *f_file = f->priv;
 	unsigned long lastofs;
diff --git a/fs/nfs.c b/fs/nfs.c
index c58fca7..43476d1 100644
--- a/fs/nfs.c
+++ b/fs/nfs.c
@@ -928,7 +928,7 @@
 	nfs_len = len;
 }
 
-static int nfs_truncate(struct device_d *dev, FILE *f, ulong size)
+static int nfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	return -ENOSYS;
 }
diff --git a/fs/omap4_usbbootfs.c b/fs/omap4_usbbootfs.c
index cc33287..169cde7 100644
--- a/fs/omap4_usbbootfs.c
+++ b/fs/omap4_usbbootfs.c
@@ -57,7 +57,7 @@
 	return -ENOSYS;
 }
 
-static int omap4_usbbootfs_truncate(struct device_d *dev, FILE *f, ulong size)
+static int omap4_usbbootfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	return -ENOSYS;
 }
diff --git a/fs/ramfs.c b/fs/ramfs.c
index 153b9b6..4fba40d 100644
--- a/fs/ramfs.c
+++ b/fs/ramfs.c
@@ -347,7 +347,7 @@
 	return insize;
 }
 
-static int ramfs_truncate(struct device_d *dev, FILE *f, ulong size)
+static int ramfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	struct inode *inode = f->f_inode;
 	struct ramfs_inode *node = to_ramfs_inode(inode);
diff --git a/fs/ratpfs.c b/fs/ratpfs.c
index dffd276..b6857c6 100644
--- a/fs/ratpfs.c
+++ b/fs/ratpfs.c
@@ -77,7 +77,7 @@
 }
 
 static int ratpfs_truncate(struct device_d __always_unused *dev,
-			  FILE *f, ulong size)
+			  FILE *f, loff_t size)
 {
 	int len_tx = 1 /* type */
 		+ 4 /* handle */
diff --git a/fs/smhfs.c b/fs/smhfs.c
index 7a69336..2e99b05 100644
--- a/fs/smhfs.c
+++ b/fs/smhfs.c
@@ -56,7 +56,7 @@
 
 static int smhfs_truncate(struct device_d __always_unused *dev,
 			  FILE __always_unused *f,
-			  ulong __always_unused size)
+			  loff_t __always_unused size)
 {
 	return 0;
 }
diff --git a/fs/tftp.c b/fs/tftp.c
index 41f904f..4329327 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -93,7 +93,7 @@
 	IPaddr_t server;
 };
 
-static int tftp_truncate(struct device_d *dev, FILE *f, ulong size)
+static int tftp_truncate(struct device_d *dev, FILE *f, loff_t size)
 {
 	return 0;
 }
diff --git a/include/fs.h b/include/fs.h
index 68b6380..aa23bcc 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -46,7 +46,7 @@
 	int (*unlink)(struct device_d *dev, const char *pathname);
 
 	/* Truncate a file to given size */
-	int (*truncate)(struct device_d *dev, FILE *f, ulong size);
+	int (*truncate)(struct device_d *dev, FILE *f, loff_t size);
 
 	int (*open)(struct device_d *dev, FILE *f, const char *pathname);
 	int (*close)(struct device_d *dev, FILE *f);