diff --git a/plugins/core.py b/plugins/core.py
index 8bf868d..d24b00f 100644
--- a/plugins/core.py
+++ b/plugins/core.py
@@ -56,6 +56,26 @@ async def cmd_version(bot, message):
     await bot.reply(message, f"derp {__version__}")
 
 
+@command("uptime", help="Show how long the bot has been running")
+async def cmd_uptime(bot, message):
+    """Report bot uptime."""
+    import time
+
+    elapsed = int(time.monotonic() - bot._started)
+    days, rem = divmod(elapsed, 86400)
+    hours, rem = divmod(rem, 3600)
+    minutes, secs = divmod(rem, 60)
+    parts = []
+    if days:
+        parts.append(f"{days}d")
+    if hours:
+        parts.append(f"{hours}h")
+    if minutes:
+        parts.append(f"{minutes}m")
+    parts.append(f"{secs}s")
+    await bot.reply(message, f"up {' '.join(parts)}")
+
+
 @command("load", help="Hot-load a plugin: !load <name>")
 async def cmd_load(bot, message):
     """Load a new plugin from the plugins directory."""
diff --git a/src/derp/bot.py b/src/derp/bot.py
index d81cad5..2f29522 100644
--- a/src/derp/bot.py
+++ b/src/derp/bot.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import logging
+import time
 from pathlib import Path
 
 from derp.irc import IRCConnection, Message, format_msg, parse
@@ -30,6 +31,7 @@ class Bot:
         self.nick: str = config["server"]["nick"]
         self.prefix: str = config["bot"]["prefix"]
         self._running = False
+        self._started: float = time.monotonic()
 
     async def start(self) -> None:
         """Connect, register, join channels, and enter the main loop."""