diff --git a/cumulus/src/CMakeLists.txt b/cumulus/src/CMakeLists.txt
index 797d56e6..ebfe627e 100644
--- a/cumulus/src/CMakeLists.txt
+++ b/cumulus/src/CMakeLists.txt
@@ -17,6 +17,7 @@
                                   ${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/surelog.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/yosys.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/blif2vst.py
                                   ${CMAKE_CURRENT_SOURCE_DIR}/designflow/pnr.py
diff --git a/cumulus/src/designflow/clean.py b/cumulus/src/designflow/clean.py
index e8bdca4d..88134d3b 100644
--- a/cumulus/src/designflow/clean.py
+++ b/cumulus/src/designflow/clean.py
@@ -1,4 +1,5 @@
 
+import shutil
 from pathlib import Path
 from doit.exceptions import TaskFailed
 from .task import FlowTask
@@ -37,6 +38,9 @@ class Clean ( FlowTask ):
                 if filePath.is_file():
                     print( '   - {:<40} [removed]'.format( filePath.as_posix() ))
                     filePath.unlink()
+                elif filePath.is_dir():
+                    print( '   - {:<40} [removed (directory)]'.format( filePath.as_posix() ))
+                    shutil.rmtree( filePath )
                 else:
                     print( '   - {}'.format( filePath.as_posix() ))
         if doExtrasClean and len(self.extrasGlobs):
diff --git a/cumulus/src/designflow/surelog.py b/cumulus/src/designflow/surelog.py
new file mode 100644
index 00000000..1622fc33
--- /dev/null
+++ b/cumulus/src/designflow/surelog.py
@@ -0,0 +1,70 @@
+
+import os.path
+import shutil
+import subprocess
+from   pathlib import Path
+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 Surelog ( FlowTask ):
+
+    @staticmethod
+    def mkRule ( rule, depends, top, incdirs=[], libdirs=[], defines=[], options=[], flags=0 ):
+        return Surelog( rule, depends, top, incdirs, libdirs, defines, options, flags )
+
+    def __init__ ( self, rule, depends, top, incdirs, libdirs, defines, options, flags ):
+        self.flags   = flags
+        self.top     = top
+        self.incdirs = incdirs
+        self.libdirs = libdirs
+        self.defines = defines
+        self.options = options
+        self.success = True
+        targets = FlowTask._normFileList( [ self.top + '.uhdm' ] )
+        depends = FlowTask._normFileList( depends )
+        super().__init__( rule, targets, depends )
+        self.addClean( targets )
+
+    def __repr__ ( self ):
+        return '<surelog {} 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, [ 'Surelog.doTask(): Include directory not found "{}"'
+                                     , '"{}"'.format( incdir ) ] )
+                return TaskFailed( e )
+        command  = [ 'surelog', '-parse' ]
+        command += [ ' '.join( self.options ) ]
+        command += [ '-D{}'.format(d) for d in self.defines ]
+        command += [ '-I{}'.format(i) for i in self.incdirs ]
+        for libdir in self.libdirs:
+            command += [ '-L', libdir ]
+        command += [ '-top', self.top ]
+        command += [ depend.as_posix() for depend in self.depends ]
+        printCommand( command )
+        status = subprocess.call( command )
+        if status != 0: return False
+        shutil.move( 'slpp_all/surelog.uhdm', self.file_target(0) )
+        return True
+
+    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
index 432855e3..cf5f27a3 100644
--- a/cumulus/src/designflow/svase.py
+++ b/cumulus/src/designflow/svase.py
@@ -37,6 +37,7 @@ class Svase ( FlowTask ):
        #if self.flags & Svase.FlagLog:
        #    self.log = Path( self.top + '.log' )
        #    targets.append( self.log )
+        targets.append( './slang-args.txt' )
         super().__init__( rule, targets, depends )
         self.addClean( targets )
 
diff --git a/cumulus/src/designflow/yosys.py b/cumulus/src/designflow/yosys.py
index 4890fb9b..312316b0 100644
--- a/cumulus/src/designflow/yosys.py
+++ b/cumulus/src/designflow/yosys.py
@@ -110,8 +110,12 @@ class Yosys ( FlowTask ):
             self.success = TaskFailed( e )
             return
         design = Path( design )
-        if   design.suffix == '.v' : self.script.append( 'read_verilog -sv {}'.format( design.as_posix() ))
-        elif design.suffix == '.il': self.script.append( 'read_ilang       {}'.format( design.as_posix() ))
+        if   design.suffix == '.v'   :
+            self.script.append( 'read_verilog -sv {}'.format( design.as_posix() ))
+        elif design.suffix == '.il'  : self.script.append( 'read_ilang       {}'.format( design.as_posix() ))
+        elif design.suffix == '.uhdm':
+            self.script.append( 'plugin -i systemverilog' )
+            self.script.append( 'read_uhdm {}'.format( design.as_posix() ))
         else:
             e = ErrorMessage( 1, 'Yosys._loadDesign(): Unsupported input format for "{}".'.format( design ))
             self.success = TaskFailed( e )
@@ -193,7 +197,7 @@ class Yosys ( FlowTask ):
             e = ErrorMessage( 1, [ 'Yosys.doTask(): File not found "{}"'
                                  , '"{}"'.format( self.liberty.as_posix() ) ] )
             return TaskFailed( e )
-       #print( 'Yosys.doTask() on "{}"'.format( self.design ))
+        #print( 'Yosys.doTask() on "{}"'.format( self.main ))
         self._loadBlackboxes()
         if self.flags & Yosys.FlagSystemVerilog:
             self._loadSVDesign()