diff --git a/static/widgets/fontscale.ts b/static/widgets/fontscale.ts
index e9b2ebabc23..6a972e1d8d2 100644
--- a/static/widgets/fontscale.ts
+++ b/static/widgets/fontscale.ts
@@ -61,9 +61,9 @@ function makeFontSizeDropdown(elem: JQuery, obj: FontScale, buttonDropdown: JQue
     buttonDropdown.on('wheel', (e: any) => {
         e.preventDefault();
         let selectedId = elem.find('.active').index();
-        if (e.originalEvent.deltaY >= 0 && selectedId < elem.children().length - 1) {
+        if (e.originalEvent.deltaY < 0 && selectedId < elem.children().length - 1) {
             selectedId++;
-        } else if (e.originalEvent.deltaY < 0 && selectedId > 0) {
+        } else if (e.originalEvent.deltaY >= 0 && selectedId > 0) {
             selectedId--;
         }
         elem.children().eq(selectedId).trigger('click');