diff --git a/app/ui.js b/app/ui.js
index 46826221..91f056a3 100644
--- a/app/ui.js
+++ b/app/ui.js
@@ -1672,7 +1672,7 @@ const UI = {
         // Force Chrome to recalculate the layout by asking for
         // an element's dimensions
         screen.getBoundingClientRect();
-        screen.style.overflow = null;
+        screen.style.overflow = "";
     },
 
     updateDesktopName: function(rfb, name) {
diff --git a/core/util/events.js b/core/util/events.js
index 8fdf6aa6..d5e6de9e 100644
--- a/core/util/events.js
+++ b/core/util/events.js
@@ -115,7 +115,7 @@ export function setCapture (elem) {
         _captureObserver.observe(elem, {attributes:true});
         _captureElemChanged();
 
-        captureElem.style.display = null;
+        captureElem.style.display = "";
 
         // We listen to events on window in order to keep tracking if it
         // happens to leave the viewport