diff --git a/src/extension.js b/src/extension.js
index 18708d9..d4600d3 100644
--- a/src/extension.js
+++ b/src/extension.js
@@ -112,7 +112,12 @@ const TeaTimeFullscreenNotification = new Lang.Class({
 	},
 	show: function () {
 		if (typeof Layout.MonitorConstraint != 'undefined') {
-			this._monitorConstraint.index = global.screen.get_current_monitor()
+			// global.display was introduced in gnome-shell 3.30
+			if (typeof global.screen != 'undefined') {
+				this._monitorConstraint.index = global.screen.get_current_monitor();
+			} else {
+				this._monitorConstraint.index = global.display.get_current_monitor();
+			}
 		}
 		Main.pushModal(this._bin);
 		this._timeline.start();