diff --git a/cumulus/src/CMakeLists.txt b/cumulus/src/CMakeLists.txt
index f8bdc57d..ffef310b 100644
--- a/cumulus/src/CMakeLists.txt
+++ b/cumulus/src/CMakeLists.txt
@@ -16,6 +16,7 @@
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/block.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/rsave.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/rsaveall.py
+                                  ${CMAKE_CURRENT_SOURCE_DIR}/plugins/checks.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/s2r.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/aboutwindow.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/plugins/stats.py
diff --git a/cumulus/src/plugins/alpha/core2chip/core2chip.py b/cumulus/src/plugins/alpha/core2chip/core2chip.py
index 5ac19a8b..5c1e8ee8 100644
--- a/cumulus/src/plugins/alpha/core2chip/core2chip.py
+++ b/cumulus/src/plugins/alpha/core2chip/core2chip.py
@@ -47,12 +47,13 @@ from   __future__      import print_function
 from   exceptions      import NotImplementedError
 import re
 from   Hurricane       import UpdateSession, Net, Instance
-from   CRL             import Catalog, AllianceFramework
+from   CRL             import Catalog, AllianceFramework, Spice
 from   helpers         import trace, netDirectionToStr
 from   helpers.overlay import UpdateSession
 from   helpers.io      import ErrorMessage, WarningMessage
 import plugins.chip
 from   plugins.rsave                     import rsave
+from   plugins.checks                    import oneDriver
 from   plugins.alpha.utils               import getPlugByName
 from   plugins.alpha.block.block         import Block
 from   plugins.alpha.block.configuration import BlockConf, IoPadConf, ConstantsConf
@@ -713,4 +714,6 @@ class CoreToChip ( object ):
                 ioPad.udata.createPad()
             self._connectRing()
             self._connectClocks()
-        rsave( self.chip, views=Catalog.State.Logical )
+        oneDriver( self.chip )
+        rsave( self.chip, views=Catalog.State.Logical, enableSpice=True )
+        Spice.clearProperties()
diff --git a/cumulus/src/plugins/checks.py b/cumulus/src/plugins/checks.py
new file mode 100644
index 00000000..8bc6ab16
--- /dev/null
+++ b/cumulus/src/plugins/checks.py
@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+#
+# This file is part of the Coriolis Software.
+# Copyright (c) SU 2021-2021, All Rights Reserved
+#
+# +-----------------------------------------------------------------+
+# |                   C O R I O L I S                               |
+# |      C u m u l u s  -  P y t h o n   T o o l s                  |
+# |                                                                 |
+# |  Author      :                    Jean-Paul CHAPUT              |
+# |  E-mail      :            Jean-Paul.Chaput@lip6.fr              |
+# | =============================================================== |
+# |  Python      :       "./plugins/checks.py"                      |
+# +-----------------------------------------------------------------+
+
+
+from   __future__ import print_function
+import sys
+import traceback
+import os.path
+
+try:
+    import Cfg
+    import CRL
+    import helpers
+    from   helpers.io import ErrorMessage
+    from   helpers.io import WarningMessage
+    import plugins
+    from   Hurricane  import Net, Plug
+except Exception, e:
+    helpers.io.catch( e )
+    sys.exit(2)
+
+
+def oneDriver ( cell ):
+    """
+    Checks that all nets have *one and only one* driver.
+    """
+    print( '  o  Checks that all nets have exactly one drivers on "{}"'.format(cell.getName()) )
+    for net in cell.getNets():
+        if net.isGlobal() or net.isSupply():
+            continue
+        drivers = []
+        if net.isExternal():
+            if net.getDirection() & Net.Direction.IN:
+                drivers.append( net )
+            elif net.getDirection() & Net.Direction.OUT:
+                pass
+            else:
+                print( WarningMessage( [ 'checks.oneDriver(): External net without direction.'
+                                       , '{}'.format(net) ] ))
+        for plug in net.getPlugs():
+            masterNet = plug.getMasterNet()
+            if masterNet.getDirection() & Net.Direction.OUT:
+                drivers.append( plug )
+        #for pin in net.getPins():
+        #    if len(drivers) == 0:
+        #        drivers.append( pin )
+        if len(drivers) == 0:
+            print( WarningMessage( 'checks.oneDriver(): "{}" has no driver.'.format(net.getName()) ) )
+        elif len(drivers) > 1:
+            message = [ 'checks.oneDriver(): "{}" has more than one drivers.'.format(net.getName()) ]
+            for driver in drivers:
+                if isinstance(driver,Plug):
+                    message.append( '* {} {}'.format(driver,driver.getMasterNet()) )
+                else:
+                    message.append( '* {}'.format(driver) )
+            print( WarningMessage( message ))
+    return
+
+
+# --------------------------------------------------------------------
+# Plugin hook functions, unicornHook:menus, ScritMain:call
+
+def unicornHook ( **kw ):
+    """Hook up rsave plugin into Unicorn/CGT menu tree."""
+    plugins.kwUnicornHook( 'tools.checks'
+                         , 'Netlist Checks'
+                         , 'Perform coherency checks on the netlist'
+                         , sys.modules[__name__].__file__
+                         , **kw
+                         )
+    return
+
+
+def scriptMain ( **kw ):
+    """Called when run as a stand alone script through Unicorn/CGT."""
+    try:
+       #helpers.setTraceLevel( 550 )
+        cell, editor = plugins.kwParseMain( **kw )
+        if not cell:
+            print( WarningMessage( 'No Cell loaded in the editor (yet), nothing done.' ) )
+            return 0
+        oneDriver( cell )
+    except Exception, e:
+      helpers.io.catch( e )
+    sys.stdout.flush()
+    sys.stderr.flush()
+    return 0