diff --git a/cumulus/src/CMakeLists.txt b/cumulus/src/CMakeLists.txt
index 139fdaeb..4c2ce127 100644
--- a/cumulus/src/CMakeLists.txt
+++ b/cumulus/src/CMakeLists.txt
@@ -15,6 +15,8 @@
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/druc.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/graal.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/dreal.py
+                                  ${CMAKE_CURRENT_SOURCE_DIR}/designflow/sv2v.py
+                                  ${CMAKE_CURRENT_SOURCE_DIR}/designflow/svase.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/yosys.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/yosysnp.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/blif2vst.py
diff --git a/cumulus/src/designflow/sv2v.py b/cumulus/src/designflow/sv2v.py
new file mode 100644
index 00000000..177f7d21
--- /dev/null
+++ b/cumulus/src/designflow/sv2v.py
@@ -0,0 +1,77 @@
+
+import os.path
+import subprocess
+from   pathlib import Path
+from   pyosys          import libyosys as yosys
+from   doit.exceptions import TaskFailed
+from   .task           import FlowTask
+
+
+def printCommand ( command ):
+    commandBin = command[0]
+    print( commandBin, command[1] )
+    for arg in command[2:]:
+        print( ' '*len(commandBin), arg )
+
+
+class Sv2v ( FlowTask ):
+
+    FlagLog = 0x00000001
+
+    @staticmethod
+    def mkRule ( rule, targets, depends, top=None, incdirs=[], libdirs=[], defines=[], flags=0 ):
+        return Sv2v( rule, targets, depends, top, incdirs, libdirs, defines, flags )
+
+    def __init__ ( self, rule, targets, depends, top, incdirs, libdirs, defines, flags ):
+        self.flags   = flags
+        self.incdirs = incdirs
+        self.libdirs = libdirs
+        self.defines = defines
+        self.log     = None
+        self.success = True
+        targets = FlowTask._normFileList( targets )
+        depends = FlowTask._normFileList( depends )
+        if top is not None:
+            self.top = top
+        else:
+            self.top = depends[0].stem
+        if targets == []:
+            targets.append( self.top + '.v' )
+       #if self.flags & Sv2v.FlagLog:
+       #    self.log = Path( self.top + '.log' )
+       #    targets.append( self.log )
+        super().__init__( rule, targets, depends )
+        self.addClean( targets )
+
+    def __repr__ ( self ):
+        return '<sv2v {} top={}>'.format( self.main, self.top )
+
+    @property
+    def main ( self ):
+        return self.file_depend( 0 )
+
+    def doTask ( self ):
+        from ..helpers.io import ErrorMessage
+        for incdir in self.incdirs:
+            if not Path(incdir).is_dir():
+                e = ErrorMessage( 1, [ 'Sv2v.doTask(): Include directory not found "{}"'
+                                     , '"{}"'.format( incdir ) ] )
+                return TaskFailed( e )
+        command  = [ 'sv2v' ]
+        command += [ '--define={}'.format(d) for d in self.defines ]
+        command += [ '--incdir={}'.format(i) for i in self.incdirs ]
+        command += [ '--libdir={}'.format(l) for l in self.libdirs ]
+        command += [ '--top={}'.format( self.top ) ]
+        command += [ depend.as_posix() for depend in self.depends ]
+        printCommand( command )
+        with open( self.file_target(), 'w' ) as fdOut:
+            status = subprocess.call( command, stdout=fdOut )
+        return status == 0
+
+    def create_doit_tasks ( self ):
+        return { 'basename' : self.basename
+               , 'actions'  : [ self.doTask ]
+               , 'doc'      : 'Run {}.'.format( self )
+               , 'file_dep' : self.file_dep
+               , 'targets'  : self.targets
+               }
diff --git a/cumulus/src/designflow/svase.py b/cumulus/src/designflow/svase.py
new file mode 100644
index 00000000..ec096c7c
--- /dev/null
+++ b/cumulus/src/designflow/svase.py
@@ -0,0 +1,86 @@
+
+import os.path
+import subprocess
+from   pathlib import Path
+from   pyosys          import libyosys as yosys
+from   doit.exceptions import TaskFailed
+from   .task           import FlowTask
+
+
+def printCommand ( command ):
+    commandBin = command[0]
+    print( commandBin, command[1] )
+    for arg in command[2:]:
+        print( ' '*len(commandBin), arg )
+
+
+class Svase ( FlowTask ):
+
+    FlagLog = 0x00000001
+
+    @staticmethod
+    def mkRule ( rule, targets, depends, top=None, incdirs=[], libdirs=[], defines=[], svargs=[], flags=0 ):
+        return Svase( rule, targets, depends, top, incdirs, libdirs, defines, svargs, flags )
+
+    def __init__ ( self, rule, targets, depends, top, incdirs, libdirs, defines, svargs, flags ):
+        self.flags   = flags
+        self.svargs  = svargs
+        self.incdirs = incdirs
+        self.libdirs = libdirs
+        self.defines = defines
+        self.log     = None
+        self.success = True
+        targets = FlowTask._normFileList( targets )
+        depends = FlowTask._normFileList( depends )
+        if top is not None:
+            self.top = top
+        else:
+            self.top = depends[0].stem
+        if targets == []:
+            targets.append( self.top + '.v' )
+       #if self.flags & Svase.FlagLog:
+       #    self.log = Path( self.top + '.log' )
+       #    targets.append( self.log )
+        super().__init__( rule, targets, depends )
+        self.addClean( targets )
+
+    def __repr__ ( self ):
+        return '<svase top={} {} {}>'.format( self.top, self.file_target(0), self.main )
+
+    @property
+    def main ( self ):
+        return self.file_depend( 0 )
+
+    def doTask ( self ):
+        from ..helpers.io import ErrorMessage
+        for incdir in self.incdirs:
+            if not Path(incdir).is_dir():
+                e = ErrorMessage( 1, [ 'Svase.doTask(): Include directory not found.'
+                                     , '"{}"'.format( incdir ) ] )
+                return TaskFailed( e )
+        with open( 'slang-args.txt', 'w' ) as fdSlangArgs:
+            for svarg in self.svargs:
+                fdSlangArgs.write( '{}\n'.format(svarg) )
+            for define in self.defines:
+                fdSlangArgs.write( '-D{}\n'.format(define) )
+            for incdir in self.incdirs:
+                fdSlangArgs.write( '--include-directory {}\n'.format(incdir) )
+            for libdir in self.libdirs:
+                fdSlangArgs.write( '--libdir {}\n'.format(libdir) )
+
+        command  = [ 'svase' ]
+        command += [ '--slang-argfile=slang-args.txt' ]
+        command += [ self.top ]
+        command += [ self.file_target(0) ]
+        command += [ depend.as_posix() for depend in self.depends ]
+        printCommand( command )
+        status = subprocess.call( command )
+        return status == 0
+
+    def create_doit_tasks ( self ):
+        return { 'basename' : self.basename
+               , 'actions'  : [ self.doTask ]
+               , 'doc'      : 'Run {}.'.format( self )
+               , 'file_dep' : self.file_dep
+               , 'targets'  : self.targets
+               }
diff --git a/cumulus/src/designflow/yosys.py b/cumulus/src/designflow/yosys.py
index bc7ff40d..69e55a60 100644
--- a/cumulus/src/designflow/yosys.py
+++ b/cumulus/src/designflow/yosys.py
@@ -65,8 +65,9 @@ class Yosys ( FlowTask ):
             e = ErrorMessage( 1, 'Yosys._loadDesign(): Can\'t find design file "{}".'.format( design ))
             self.success = TaskFailed( e )
             return
-        if   design.suffix == '.v' : self._run_pass( 'read_verilog {}'.format( design.as_posix() ))
-        elif design.suffix == '.il': self._run_pass( 'read_ilang   {}'.format( design.as_posix() ))
+        design = Path( design )
+        if   design.suffix == '.v' : self._run_pass( 'read_verilog -sv {}'.format( design.as_posix() ))
+        elif design.suffix == '.il': self._run_pass( 'read_ilang       {}'.format( design.as_posix() ))
         else:
             e = ErrorMessage( 1, 'Yosys._loadDesign(): Unsupported input format for "{}".'.format( design ))
             self.success = TaskFailed( e )