diff --git a/src/app/components/Header/contents.tsx b/src/app/components/Header/contents.tsx
index f625da1..b280652 100644
--- a/src/app/components/Header/contents.tsx
+++ b/src/app/components/Header/contents.tsx
@@ -37,7 +37,9 @@ export const HeaderContent = ({ user }: { user?: User }) => {
 	const selectedClass = classes.find((Class) => Class.id === selectedClassId);
 
 	useEffect(() => {
-		setSelectedClassId(classes[0]?.id ?? null);
+		if (!selectedClass && classes.length > 0) {
+			setSelectedClassId(classes[0].id);
+		}
 	}, [selectedClass, classes, setSelectedClassId]);
 
 	return (