diff --git a/src/pyarcanist/__init__.py b/src/pyarcanist/__init__.py
index 757856e..514ec32 100644
--- a/src/pyarcanist/__init__.py
+++ b/src/pyarcanist/__init__.py
@@ -1,9 +1,10 @@
 from .cache import cache
 from . import cli
 
 # make sure these are imported after cli, since some
 # cache config may occur in there
 from . import whoami
 from . import diff
+from . import harbormaster
 
 __all__ = (cli, whoami, diff, cache)
diff --git a/src/pyarcanist/harbormaster.py b/src/pyarcanist/harbormaster.py
new file mode 100644
index 0000000..fd8af41
--- /dev/null
+++ b/src/pyarcanist/harbormaster.py
@@ -0,0 +1,84 @@
+import click
+from . import cli
+
+
+validators = {
+    'unit': [
+        ('name', True, None),
+        ('result', True,
+         ('pass', 'fail', 'skip', 'broken', 'unsound')),
+        ('namespace', False, None),
+        ('engine', False, None),
+        ('duration', False, float),
+        ('path', False, None),
+        ('coverage', False, None),
+        ('details', False, None),
+        ('format', False, None),
+    ],
+    'lint': [
+        ('name', True, None),
+        ('code', True, None),
+        ('severity', True,
+         ('advice', 'autofix', 'warning', 'error', 'disabled')),
+        ('path', True, None),
+        ('line', False, int),
+        ('char', False, int),
+        ('description', False, None),
+    ],
+}
+
+
+def check_validator(validator, value):
+    if not validator:
+        return True
+    if isinstance(validator, tuple):
+        return value in validator
+    if callable(validator):
+        try:
+            validator(value)
+        except Exception:
+            return False
+    return True
+
+
+def validate(params, report_type):
+    if isinstance(params, str):
+        params = dict(x.strip().split('=', 1) for x in params.split(','))
+    for k, mandatory, validator in validators[report_type]:
+        if mandatory and not k in params:
+            raise ValueError(
+                'Parameter {} is mandatory for a {} report'.format(
+                    k, report_type))
+        if k in params and not check_validator(validator, params[k]):
+            raise ValueError(
+                'Parameter {} has an invalid value "{}"'.format(k, params[k]))
+    return params
+
+
+@cli.pyarc.command()
+@click.argument('message-type', type=click.Choice(['pass', 'fail', 'work']))
+@click.argument('phid')
+@click.option('-u', '--unit', multiple=True)
+@click.option('-l', '--lint', multiple=True)
+@click.pass_context
+def send_message(ctx, message_type, phid, unit, lint):
+    '''Send a harbormaster message'''
+
+    options = ctx.obj['options']
+
+    kw = {'type': message_type,
+          'buildTargetPHID': phid}
+    try:
+        if unit:
+            kw['unit'] = [validate(u, 'unit') for u in unit]
+        if lint:
+            kw['lint'] = [validate(l, 'lint') for l in lint]
+    except ValueError as e:
+
+        ctx.fail('Invalid parameter: {}'. format(e))
+
+    if options.verbose:
+        click.echo('Sending message to harbormaster:')
+        for k, v in kw.items():
+            click.echo("  {}: {}".format(k, v))
+    cli.cnx.harbormaster.sendmessage(**kw)