diff --git a/download.py b/download.py
index 8e8f15a..5c99992 100644
--- a/download.py
+++ b/download.py
@@ -204,7 +204,7 @@ class FetchCommand(click.Command):
     def invoke(self, ctx: click.Context):
         year = ctx.params.get("year")
         day = ctx.params.get("day")
-        if (year and not day) or (not day and year):
+        if (year and not day) or (day and not year):
             raise click.ClickException("day and year must be specified together")
 
         return super().invoke(ctx)