diff --git a/packages/web/src/icons/expandIcons.ts b/packages/web/src/icons/expandIcons.ts
index 3e98f7ceb..6a210fcbb 100644
--- a/packages/web/src/icons/expandIcons.ts
+++ b/packages/web/src/icons/expandIcons.ts
@@ -1,7 +1,7 @@
-export function plusExpandIcon(isExpanded) {
+export function plusExpandIcon(isExpanded): string {
   return isExpanded ? 'icon minus-box' : 'icon plus-box';
 }
 
-export function chevronExpandIcon(isExpanded) {
+export function chevronExpandIcon(isExpanded): string {
   return isExpanded ? 'icon chevron-down' : 'icon chevron-right';
 }