diff --git a/mmcli/mmcli.py b/mmcli/mmcli.py
index be11030..fb9e834 100755
--- a/mmcli/mmcli.py
+++ b/mmcli/mmcli.py
@@ -44,6 +44,12 @@ def warn_if_tty(you_can_type="the message objects", write_message_to=sys.stderr)
 		print(f"Reading from tty. (You can type {you_can_type} below. Or maybe you meant to redirect something to stdin.)", file=write_message_to)
 
 
+def get_user_id(mm_api: mattermost.MMApi):
+	if mm_api._my_user_id is None:
+		mm_api._my_user_id = mm_api.get_user()["id"]
+	return mm_api._my_user_id
+
+
 def get_posts_for_channel(self, channel_id: str, progress=lambda x: None, after=None, **kwargs) -> Iterable[Dict]:
 	"""
 	@raises ApiException: Passed on from lower layers.
@@ -418,16 +424,24 @@ def edit(mm_api: mattermost.MMApi, cmdline_args):
 	mm_api.patch_post(cmdline_args.msgid, message=new_text)
 
 
+def addreaction(mm_api: mattermost.MMApi, cmdline_args):
+	# "me" does not work here, explicit user ID required. (sigh)
+	mm_api.create_reaction(get_user_id(mm_api), cmdline_args.msgid, cmdline_args.emoji_name)
+
+
+def removereaction(mm_api: mattermost.MMApi, cmdline_args):
+	# pylint: disable=protected-access # library recommends this in docs
+	mm_api._delete(f"/v4/users/me/posts/{cmdline_args.msgid}/reactions/{cmdline_args.emoji_name}")
+
+
 def status(mm_api: mattermost.MMApi, cmdline_args):
 	if not cmdline_args.status:
 		raise ValueError("No status selected")
 
-	# This API endpoint requires the user ID to be passed explicitly in the request body,
-	# duplicating the info in the URL. But "me" does not suffice here.
-	my_user_id = mm_api.get_user()["id"]
-
 	mm_api._put(f"/v4/users/me/status", data={
-		"user_id": my_user_id,
+		# This API endpoint requires the user ID to be passed explicitly in the request body,
+		# duplicating the info in the URL. But "me" does not work here here. (sigh)
+		"user_id": get_user_id(mm_api),
 		"status": cmdline_args.status
 	})
 
@@ -505,6 +519,8 @@ ACTIONS = {
 	"send": {"function": send},
 	"rm": {"function": rm},
 	"edit": {"function": edit},
+	"addreaction": {"function": addreaction},
+	"removereaction": {"function": removereaction},
 	"status": {"function": status},
 	"customstatus": {"function": customstatus},
 	"lastread": {"function": lastread},
@@ -606,6 +622,16 @@ The input format accepted on stdin is one JSON object per line. The possible fie
 	parser_edit.add_argument(
 		"--message", help="message; if not provided, message will be expected on stdin")
 
+	parser_addreaction = subparsers.add_parser(
+		"addreaction", help="add emoji reaction to a message")
+	parser_addreaction.add_argument("msgid", help="ID of message")
+	parser_addreaction.add_argument("emoji_name", help="name of the emoji to add (without colons)")
+
+	parser_removereaction = subparsers.add_parser(
+		"removereaction", help="remove emoji reaction from a message")
+	parser_removereaction.add_argument("msgid", help="ID of message")
+	parser_removereaction.add_argument("emoji_name", help="name of the emoji to remove (without colons)")
+
 	parser_status = subparsers.add_parser("status", help="update user status")
 	parser_status.add_argument("--online",  dest="status", action="store_const", const="online",  help="Set status to online")
 	parser_status.add_argument("--away",    dest="status", action="store_const", const="away",    help="Set status to away")