diff --git a/hw/xwayland/xwayland-glamor-gbm.c b/hw/xwayland/xwayland-glamor-gbm.c
index 80655fd16..17682a172 100644
--- a/hw/xwayland/xwayland-glamor-gbm.c
+++ b/hw/xwayland/xwayland-glamor-gbm.c
@@ -49,6 +49,7 @@
 #include "xwayland-glamor.h"
 #include "xwayland-pixmap.h"
 #include "xwayland-screen.h"
+#include "xwayland-window.h"
 
 #include "linux-dmabuf-unstable-v1-client-protocol.h"
 
@@ -919,6 +920,14 @@ xwl_glamor_gbm_has_wl_interfaces(struct xwl_screen *xwl_screen)
     return TRUE;
 }
 
+static void
+xwl_glamor_gbm_post_damage(struct xwl_window *xwl_window, PixmapPtr pixmap,
+                           RegionPtr region)
+{
+    /* Make sure any pending drawing to the pixmap is flushed to the kernel */
+    glamor_block_handler(xwl_window->xwl_screen->screen);
+}
+
 static Bool
 xwl_glamor_gbm_init_egl(struct xwl_screen *xwl_screen)
 {
@@ -1111,5 +1120,6 @@ xwl_glamor_init_gbm(struct xwl_screen *xwl_screen)
     xwl_screen->gbm_backend.init_egl = xwl_glamor_gbm_init_egl;
     xwl_screen->gbm_backend.init_screen = xwl_glamor_gbm_init_screen;
     xwl_screen->gbm_backend.get_wl_buffer_for_pixmap = xwl_glamor_gbm_get_wl_buffer_for_pixmap;
+    xwl_screen->gbm_backend.post_damage = xwl_glamor_gbm_post_damage;
     xwl_screen->gbm_backend.is_available = TRUE;
 }
diff --git a/hw/xwayland/xwayland-glamor.c b/hw/xwayland/xwayland-glamor.c
index d9523b0a7..f3327f4ee 100644
--- a/hw/xwayland/xwayland-glamor.c
+++ b/hw/xwayland/xwayland-glamor.c
@@ -124,8 +124,7 @@ xwl_glamor_post_damage(struct xwl_window *xwl_window,
 {
     struct xwl_screen *xwl_screen = xwl_window->xwl_screen;
 
-    if (xwl_screen->egl_backend->post_damage)
-        xwl_screen->egl_backend->post_damage(xwl_window, pixmap, region);
+    xwl_screen->egl_backend->post_damage(xwl_window, pixmap, region);
 }
 
 Bool
diff --git a/hw/xwayland/xwayland-glamor.h b/hw/xwayland/xwayland-glamor.h
index e9896bfef..138accd6d 100644
--- a/hw/xwayland/xwayland-glamor.h
+++ b/hw/xwayland/xwayland-glamor.h
@@ -70,10 +70,8 @@ struct xwl_egl_backend {
                                                   Bool *created);
 
     /* Called by Xwayland to perform any pre-wl_surface damage routines
-     * that are required by the backend. If your backend is poorly
-     * designed and lacks the ability to render directly to a surface,
-     * you should implement blitting from the glamor pixmap to the wayland
-     * pixmap here. Otherwise, this callback is optional.
+     * that are required by the backend to make sure any pending drawing
+     * operations to the pixmap will be visible to the Wayland server.
      */
     void (*post_damage)(struct xwl_window *xwl_window,
                         PixmapPtr pixmap, RegionPtr region);