diff --git a/lib/PositionManager.vala b/lib/PositionManager.vala
index e1dfa447..a430cd1a 100644
--- a/lib/PositionManager.vala
+++ b/lib/PositionManager.vala
@@ -65,7 +65,7 @@ namespace Plank
 			screen.composited_changed.connect (screen_composited_changed);
 			
 			// NOTE don't call update_monitor_geo to avoid a double-call of dockwindow.set_size on startup
-			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU)) {
+			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU | XdgSessionDesktop.MATE)) {
 				screen.get_monitor_geometry (find_monitor_number (screen, controller.prefs.Monitor), out monitor_geo);
 			} else {
 				monitor_geo = screen.get_monitor_workarea (find_monitor_number (screen, controller.prefs.Monitor));
@@ -137,10 +137,14 @@ namespace Plank
 		void screen_changed (Gdk.Screen screen)
 		{
 			var old_monitor_geo = monitor_geo;
+
+			Logger.verbose ("screen_changed()");
 			
-			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU)) {
+			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU | XdgSessionDesktop.MATE)) {
+				Logger.verbose ("Gnome, Ubuntu or Mate.");
 				screen.get_monitor_geometry (find_monitor_number (screen, controller.prefs.Monitor), out monitor_geo);
 			} else {
+				Logger.verbose ("Another XdgSessionDesktop env.");
 				monitor_geo = screen.get_monitor_workarea (find_monitor_number (screen, controller.prefs.Monitor));
 			}
 			
diff --git a/lib/Services/Environment.vala b/lib/Services/Environment.vala
index e7f7db29..0544795f 100644
--- a/lib/Services/Environment.vala
+++ b/lib/Services/Environment.vala
@@ -154,7 +154,7 @@ namespace Plank
 	
 	public static bool environment_is_session_desktop (XdgSessionDesktop type)
 	{
-		return (type in session_desktop);
+		return (type & session_desktop) > 0;
 	}
 	
 	public static bool environment_is_session_type (XdgSessionType type)
diff --git a/lib/Widgets/HoverWindow.vala b/lib/Widgets/HoverWindow.vala
index 47b747d0..02c88f00 100644
--- a/lib/Widgets/HoverWindow.vala
+++ b/lib/Widgets/HoverWindow.vala
@@ -76,7 +76,7 @@ namespace Plank
 		{
 			unowned Gdk.Screen screen = get_screen ();
 			Gdk.Rectangle monitor;
-			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU)) {
+			if (environment_is_session_desktop (XdgSessionDesktop.GNOME | XdgSessionDesktop.UBUNTU | XdgSessionDesktop.MATE)) {
 				screen.get_monitor_geometry (screen.get_monitor_at_point (x, y), out monitor);
 			} else {
 				monitor = screen.get_monitor_workarea (screen.get_monitor_at_point (x, y));