diff --git a/aheui/aheui.py b/aheui/aheui.py
index b72ccf3..f04962c 100644
--- a/aheui/aheui.py
+++ b/aheui/aheui.py
@@ -10,7 +10,7 @@
 from aheui._compat import jit, unichr, ord, _unicode, bigint, PYR
 from aheui import compile
 from aheui.option import process_options, OptionError
-from aheui.warning import WarningPool
+from aheui.warning import NoRpythonWarning, WriteUtf8RangeWarning, warnings
 
 
 def get_location(pc, stackok, is_queue, program):
@@ -283,7 +283,7 @@ def write_number(value_str):
     os.write(outfp, value_str)
 
 
-def write_utf8(warnings, value):
+def write_utf8(value):
     REPLACE_CHAR = unichr(0xfffd).encode('utf-8')
 
     if bigint.is_unicodepoint(value):
@@ -296,8 +296,8 @@ def write_utf8(warnings, value):
     os.write(outfp, bytes)
 
 
-def warn_utf8_range(warnings, value):
-    warnings.warn(b'write-utf8-range', value)
+def warn_utf8_range(value):
+    warnings.warn(WriteUtf8RangeWarning, value)
     os.write(outfp, unichr(0xfffd).encode('utf-8'))
 
 class Program(object):
@@ -328,7 +328,6 @@ def get_label(self, pc):
 
 outfp = 1
 errfp = 2
-warnings = WarningPool()
 
 
 def mainloop(program, debug):
@@ -422,7 +421,7 @@ def mainloop(program, debug):
             write_number(bigint.str(r))
         elif op == c.OP_POPCHAR:
             r = selected.pop()
-            write_utf8(warnings, r)
+            write_utf8(r)
         elif op == c.OP_PUSHNUM:
             num = read_number()
             selected.push(num)
@@ -499,7 +498,7 @@ def entry_point(argv):
     outfp = 1 if output == '-' else open_w(output)
     if target == 'run':
         if not PYR:
-            warnings.warn(b'no-rpython')
+            warnings.warn(NoRpythonWarning)
         program = Program(compiler.lines, compiler.label_map)
         exitcode = mainloop(program, compiler.debug)
     elif target in ['asm', 'asm+comment']:
diff --git a/aheui/option.py b/aheui/option.py
index d22f160..23ef81e 100644
--- a/aheui/option.py
+++ b/aheui/option.py
@@ -6,6 +6,7 @@
 from aheui._argparse import ArgumentParser, ParserError
 from aheui._compat import bigint, PY3
 from aheui.version import VERSION
+from aheui.warning import CommandLineArgumentWarning, warnings
 from aheui import compile
 
 
@@ -56,16 +57,16 @@ def message(self):
         return 'The value of %s="%s" is not a valid integer' % self.args
 
 
-class SourceError(Exception):
+class SourceError(OptionError):
     pass
 
 
-class NoInputError(Exception):
+class NoInputError(SourceError):
     def message(self):
         return "no input files"
 
 
-class CommandConflictInputFileError(Exception):
+class CommandConflictInputFileError(SourceError):
     def message(self):
         return "--cmd,-c and input file cannot be used together"
 
@@ -177,6 +178,9 @@ def process_options(argv, environ):
         else:
             assert False  # must be handled by argparse
             raise SystemExit()
+    else:
+        if target == 'run':
+            warnings.warn(CommandLineArgumentWarning, '--target=run always ignores --output')
 
     warning_limit = kwarg_or_environ_int(kwargs, environ, 'warning-limit', 'RPAHEUI_WARNING_LIMIT', 3)
     trace_limit = kwarg_or_environ_int(kwargs, environ, 'trace-limit', 'RPAHEUI_TRACE_LIMIT', -1)
diff --git a/aheui/warning.py b/aheui/warning.py
index e8f7265..0060f63 100644
--- a/aheui/warning.py
+++ b/aheui/warning.py
@@ -5,36 +5,46 @@
 
 
 class Warning(object):
-    def __init__(self, name, message):
-        self.name = name
-        self.message = message
-
     def format(self, *args):
-        return self.message % args
+        return self.MESSAGE % args
+    
+
+class NoRpythonWarning(Warning):
+    MESSAGE = b"[Warning:VirtualMachine] Running without rlib/jit."
+
+
+class CommandLineArgumentWarning(Warning):
+    MESSAGE = b"[Warning:CommandLine] Invalid command line argument is ignored: %s."
+
+
+class WriteUtf8RangeWarning(Warning):
+    MESSAGE = b'[Warning:UndefinedBehavior:write-utf8-range] value %x is out of unicode codepoint range.'
 
 
 WARNING_LIST = [
-    Warning(b'no-rpython', b"[Warning:VirtualMachine] Running without rlib/jit.\n"),
-    Warning(b'write-utf8-range', b'[Warning:UndefinedBehavior:write-utf8-range] value %x is out of unicode codepoint range.'),
+    NoRpythonWarning(),
+    CommandLineArgumentWarning(),
+    WriteUtf8RangeWarning(),
 ]
 
 
 class WarningPool(object):
     def __init__(self):
         self.limit = -1
-        self.warnings = {}
         self.counters = {}
         for w in WARNING_LIST:
-            self.warnings[w.name] = w
-            self.counters[w.name] = 0
+            self.counters[type(w).__name__] = 0
 
     @jit.dont_look_inside
-    def warn(self, name, *args):
-        warning = self.warnings[name]
+    def warn(self, warning, *args):
+        name = warning.__name__
         if self.limit != -1 and self.limit <= self.counters[name]:
             return
         self.counters[name] = self.counters[name] + 1
-        os.write(2, warning.format(*args))
+        os.write(2, warning().format(*args))
         os.write(2, b'\n')
         if self.limit != -1 and self.limit <= self.counters[name]:
-            os.write(2, b"[Warning:Meta] The warning '%s' has reached the limit %d and will be suppressed\n" % (warning.name, self.limit))
+            os.write(2, b"[Warning:Meta] The warning '%s' has reached the limit %d and will be suppressed\n" % (name, self.limit))
+
+
+warnings = WarningPool()