diff --git a/mouse-driver/mousek.c b/mouse-driver/mousek.c
index 376a545..449dd1f 100644
--- a/mouse-driver/mousek.c
+++ b/mouse-driver/mousek.c
@@ -65,6 +65,12 @@
 
 int Major;
 
+static int mousek_open(struct inode *inode, struct file *filp);
+static int mousek_release(struct inode *inode, struct file *filp);
+static ssize_t mousek_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos);
+static ssize_t mousek_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos);
+
+
 /*
  * We need a local data structure, as it must be allocated for each new
  * mouse device plugged in the USB bus
@@ -176,7 +182,9 @@
 	/* accept 16 bytes at a time, at most */
 	if (count > 16)
 		count = 16;
-	copy_from_user(localbuf, buf, count);
+	if (copy_from_user(localbuf, buf, count)) {
+		return -EFAULT;
+	}
 
 	/* prepare the urb for mousek_irq() */
 	// urb.status = USB_ST_NOERROR;
@@ -530,4 +538,4 @@
 	// ret = free_irq(BUTTON_IRQ, mousek_interrupt);
 	// if (ret < 0)
 	//	printk(KERN_ALERT "Error in freeing irq: %d\n", ret);
-}
\ No newline at end of file
+}