diff --git a/src/wayland/meta-wayland-wl-shell.c b/src/wayland/meta-wayland-wl-shell.c
index 2557eea64..29b89f654 100644
--- a/src/wayland/meta-wayland-wl-shell.c
+++ b/src/wayland/meta-wayland-wl-shell.c
@@ -400,6 +400,10 @@ wl_shell_surface_set_title (struct wl_client   *client,
     surface_from_wl_shell_surface_resource (resource);
 
   g_clear_pointer (&wl_shell_surface->title, g_free);
+
+  if (!g_utf8_validate (title, -1, NULL))
+    title = "";
+
   wl_shell_surface->title = g_strdup (title);
 
   if (surface->window)
@@ -417,6 +421,10 @@ wl_shell_surface_set_class (struct wl_client *client,
     surface_from_wl_shell_surface_resource (resource);
 
   g_clear_pointer (&wl_shell_surface->wm_class, g_free);
+
+  if (!g_utf8_validate (class_, -1, NULL))
+    class_ = "";
+
   wl_shell_surface->wm_class = g_strdup (class_);
 
   if (surface->window)
diff --git a/src/wayland/meta-wayland-xdg-shell.c b/src/wayland/meta-wayland-xdg-shell.c
index 4c5e972ed..240970c08 100644
--- a/src/wayland/meta-wayland-xdg-shell.c
+++ b/src/wayland/meta-wayland-xdg-shell.c
@@ -136,6 +136,9 @@ xdg_surface_set_title (struct wl_client   *client,
 {
   MetaWaylandSurface *surface = surface_from_xdg_surface_resource (resource);
 
+  if (!g_utf8_validate (title, -1, NULL))
+    title = "";
+
   meta_window_set_title (surface->window, title);
 }
 
@@ -146,6 +149,9 @@ xdg_surface_set_app_id (struct wl_client   *client,
 {
   MetaWaylandSurface *surface = surface_from_xdg_surface_resource (resource);
 
+  if (!g_utf8_validate (app_id, -1, NULL))
+    app_id = "";
+
   meta_window_set_wm_class (surface->window, app_id, app_id);
 }