diff --git a/calmerge/config.py b/calmerge/config.py
index 2eaedc4..44e6f77 100644
--- a/calmerge/config.py
+++ b/calmerge/config.py
@@ -54,7 +54,7 @@ def expand_url_vars(cls, urls: list[str]) -> list[str]:
 
 
 class Config(BaseModel):
-    calendars: list[CalendarConfig] = Field(alias="calendar")
+    calendars: list[CalendarConfig] = Field(alias="calendar", default_factory=list)
 
     @classmethod
     def from_file(cls, path: Path):
diff --git a/tests/test_config.py b/tests/test_config.py
index cc2fa1c..13f757b 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -2,7 +2,7 @@
 from pydantic import ValidationError
 from pydantic_core import Url
 
-from calmerge.config import AuthConfig, CalendarConfig
+from calmerge.config import AuthConfig, CalendarConfig, Config
 
 
 def test_non_unique_urls():
@@ -34,3 +34,7 @@ def test_expand_unknown_var():
 
     assert auth_config.username == "$FOO"
     assert auth_config.password == "${FOO}BAR"
+
+
+def test_empty_config():
+    Config()