diff --git a/drivers/memory/memory.c b/drivers/memory/memory.c
index 4b57ade42..63ff16c71 100644
--- a/drivers/memory/memory.c
+++ b/drivers/memory/memory.c
@@ -46,11 +46,14 @@ PRIVATE struct kinfo kinfo;		/* kernel information */
 
 extern int errno;			/* error number for PM calls */
 
+PRIVATE int openct[NR_DEVS];
+
 FORWARD _PROTOTYPE( char *m_name, (void) 				);
 FORWARD _PROTOTYPE( struct device *m_prepare, (int device) 		);
 FORWARD _PROTOTYPE( int m_transfer, (int proc_nr, int opcode, u64_t position,
 				iovec_t *iov, unsigned nr_req, int safe));
 FORWARD _PROTOTYPE( int m_do_open, (struct driver *dp, message *m_ptr) 	);
+FORWARD _PROTOTYPE( int m_do_close, (struct driver *dp, message *m_ptr)	);
 FORWARD _PROTOTYPE( void m_init, (void) );
 FORWARD _PROTOTYPE( int m_ioctl, (struct driver *dp, message *m_ptr, int safe));
 FORWARD _PROTOTYPE( void m_geometry, (struct partition *entry) 		);
@@ -59,7 +62,7 @@ FORWARD _PROTOTYPE( void m_geometry, (struct partition *entry) 		);
 PRIVATE struct driver m_dtab = {
   m_name,	/* current device's name */
   m_do_open,	/* open or mount */
-  do_nop,	/* nothing on a close */
+  m_do_close,	/* nothing on a close */
   m_ioctl,	/* specify ram disk geometry */
   m_prepare,	/* prepare for I/O on a given minor device */
   m_transfer,	/* do the I/O */
@@ -307,9 +310,40 @@ message *m_ptr;
 		return r;
 	}
   }
+
+  if(m_device < 0 || m_device >= NR_DEVS) {
+      panic("MEM","wrong m_device",m_device);
+  }
+
+  openct[m_device]++;
+
   return(OK);
 }
 
+/*===========================================================================*
+ *				m_do_close				     *
+ *===========================================================================*/
+PRIVATE int m_do_close(dp, m_ptr)
+struct driver *dp;
+message *m_ptr;
+{
+  int r;
+
+  if (m_prepare(m_ptr->DEVICE) == NIL_DEV) return(ENXIO);
+
+  if(m_device < 0 || m_device >= NR_DEVS) {
+      panic("MEM","wrong m_device",m_device);
+  }
+
+  if(openct[m_device] < 1) {
+      panic("MEM","closed too often",NO_NUM);
+  }
+  openct[m_device]--;
+
+  return(OK);
+}
+
+
 /*===========================================================================*
  *				m_init					     *
  *===========================================================================*/
@@ -343,6 +377,9 @@ PRIVATE void m_init()
        dev_zero[i] = '\0';
   }
 
+  for(i = 0; i < NR_DEVS; i++)
+	openct[i] = 0;
+
   /* Set up memory range for /dev/mem. */
   m_geom[MEM_DEV].dv_base = cvul64(0);
   m_geom[MEM_DEV].dv_size = cvul64(0xffffffff);
@@ -393,9 +430,20 @@ int safe;
 	if(m_vaddrs[dev] && !cmp64(dv->dv_size, cvul64(ramdev_size))) {
 		return(OK);
 	}
+	/* openct is 1 for the ioctl(). */
+	if(openct[dev] != 1) {
+		printf("MEM: MIOCRAMSIZE: %d in use (count %d)\n",
+			dev, openct[dev]);
+		return(EBUSY);
+	}
 	if(m_vaddrs[dev]) {
-		printf("MEM: MIOCRAMSIZE: %d already has a ramdisk\n", dev);
-		return(EPERM);
+		u32_t size;
+		if(ex64hi(dv->dv_size)) {
+			panic("MEM","huge old ramdisk", NO_NUM);
+		}
+		size = ex64lo(dv->dv_size);
+		munmap((void *) m_vaddrs[dev], size);
+		m_vaddrs[dev] = (vir_bytes) NULL;
 	}
 
 #if DEBUG