diff --git a/services/web/frontend/js/features/pdf-preview/components/pdf-js-viewer.tsx b/services/web/frontend/js/features/pdf-preview/components/pdf-js-viewer.tsx
index 216c47c6d9..01650346bb 100644
--- a/services/web/frontend/js/features/pdf-preview/components/pdf-js-viewer.tsx
+++ b/services/web/frontend/js/features/pdf-preview/components/pdf-js-viewer.tsx
@@ -446,6 +446,7 @@ function PdfJsViewer({ url, pdfFile }: PdfJsViewerProps) {
       }
       if (event.metaKey || event.ctrlKey) {
         switch (event.key) {
+          case '+':
           case '=':
             event.preventDefault()
             setZoom('zoom-in')