diff --git a/cogs/calendar.py b/cogs/calendar.py
index 89adbd5..f76f6f4 100644
--- a/cogs/calendar.py
+++ b/cogs/calendar.py
@@ -19,7 +19,7 @@ FIRESTORE_CALENDAR = (
 DATE_RE = re.compile(r"^\d{4}-\d{2}-\d{2}$")
 TIME_RE = re.compile(r"^\d{2}:\d{2}$")
 
-from .calendar_data import COUNTRY_TZ, tz_choices
+from .calendar_data import COUNTRY_TZ, country_autocomplete
 
 
 class Calendar(commands.Cog):
@@ -43,7 +43,7 @@ class Calendar(commands.Cog):
         title="Event title",
         description="Extra notes (optional)",
     )
-    @app_commands.choices(country=tz_choices())
+    @app_commands.autocomplete(country=country_autocomplete)
     async def book_cmd(
         self,
         interaction: discord.Interaction,
diff --git a/cogs/calendar_data.py b/cogs/calendar_data.py
index 2bbf2c1..eba2aec 100644
--- a/cogs/calendar_data.py
+++ b/cogs/calendar_data.py
@@ -48,7 +48,16 @@ COUNTRY_TZ: dict[str, float] = {
 # fmt: on
 
 
-def tz_choices() -> list:
-    """Return app_commands.Choice list for the country dropdown."""
+async def country_autocomplete(
+    _interaction,
+    current: str,
+) -> list:
+    """Return matching countries for slash-command autocomplete."""
     from discord import app_commands
-    return [app_commands.Choice(name=c, value=c) for c in sorted(COUNTRY_TZ)]
+    current = current.lower()
+    matches = [
+        app_commands.Choice(name=c, value=c)
+        for c in sorted(COUNTRY_TZ)
+        if current in c.lower()
+    ]
+    return matches[:25]  # Discord limits to 25 suggestions