diff --git a/fs/nxffs/nxffs_ioctl.c b/fs/nxffs/nxffs_ioctl.c
index d5fe2ece838..e24cf056486 100644
--- a/fs/nxffs/nxffs_ioctl.c
+++ b/fs/nxffs/nxffs_ioctl.c
@@ -47,6 +47,7 @@
 #include <debug.h>
 
 #include <nuttx/fs.h>
+#include <nuttx/ioctl.h>
 #include <nuttx/mtd.h>
 
 #include "nxffs.h"
@@ -82,6 +83,7 @@
 int nxffs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 {
   FAR struct nxffs_volume_s *volume;
+  int ret;
 
   fvdbg("cmd: %d arg: %08lx\n", cmd, arg);
 
@@ -94,7 +96,45 @@ int nxffs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
   volume = filep->f_inode->i_private;
   DEBUGASSERT(volume != NULL);
 
-  /* No ioctl commands yet supported */
+  /* Get exclusive access to the volume.  Note that the volume exclsem
+   * protects the open file list.
+   */
 
-  return -ENOTTY;
+  ret = sem_wait(&volume->exclsem);
+  if (ret != OK)
+    {
+      ret = -errno;
+      fdbg("sem_wait failed: %d\n", ret);
+      goto errout;
+    }
+
+  /* Only a reformat command is supported */
+
+  if (cmd == FIOC_REFORMAT)
+    {
+      fvdbg("Reformat command\n");
+
+      /* We cannot reformat the volume if there are any open inodes */
+
+      if (volume->ofiles)
+        {
+          fdbg("Open files\n");
+          ret = -EBUSY;
+          goto errout_with_semaphore;
+        }
+
+      /* Re-format the volume -- all is lost */
+
+      ret = nxffs_reformat(volume);
+      goto errout_with_semaphore;
+    }
+
+  /* No other commands supported */
+
+  ret = -ENOTTY;
+
+errout_with_semaphore:
+  sem_post(&volume->exclsem);
+errout:
+  return ret;
 }
diff --git a/include/nuttx/ioctl.h b/include/nuttx/ioctl.h
index 5eaf886c8aa..0c32004f8e8 100644
--- a/include/nuttx/ioctl.h
+++ b/include/nuttx/ioctl.h
@@ -94,17 +94,21 @@
                                            *      return (void*) base address
                                            *      of file
                                            */
+#define FIOC_REFORMAT   _FIOC(0x0002)     /* IN:  None
+                                           * OUT: None
+                                           */
+
 /* NuttX file system ioctl definitions */
 
 #define _DIOCVALID(c)   (_IOC_TYPE(c)==_DIOCBASE)
 #define _DIOC(nr)       _IOC(_DIOCBASE,nr)
 
-#define DIOC_GETPRIV    _DIOC(0x0001)     /* IN: Location to return handle (void **)
+#define DIOC_GETPRIV    _DIOC(0x0001)     /* IN:  Location to return handle (void **)
                                            * OUT: Reference to internal data
                                            *      structure.  May have a reference
                                            *      incremented.
                                            */
-#define DIOC_RELPRIV    _DIOC(0x0003)     /* IN: None
+#define DIOC_RELPRIV    _DIOC(0x0003)     /* IN:  None
                                            * OUT: None, reference obtained by
                                            *      FIOC_GETPRIV released.
                                            */