diff --git a/src/xrt/compositor/main/comp_target_swapchain.c b/src/xrt/compositor/main/comp_target_swapchain.c
index 16612cae2..55951cea4 100644
--- a/src/xrt/compositor/main/comp_target_swapchain.c
+++ b/src/xrt/compositor/main/comp_target_swapchain.c
@@ -150,6 +150,16 @@ select_extent(struct comp_target_swapchain *cts,
               uint32_t preferred_width,
               uint32_t preferred_height)
 {
+	/*
+	 * A sub-class wants us to use these extents over the ones the
+	 * compositor preferred, this is probably due to the target only
+	 * upporting this size so we better respect those wishes.
+	 */
+	if (cts->override.compositor_extent) {
+		preferred_width = cts->override.extent.width;
+		preferred_height = cts->override.extent.height;
+	}
+
 	// If width (and height) equals the special value 0xFFFFFFFF,
 	// the size of the surface will be set by the swapchain
 	if (caps.currentExtent.width == (uint32_t)-1) {
@@ -1032,6 +1042,25 @@ comp_target_swapchain_info_gpu(
  *
  */
 
+void
+comp_target_swapchain_override_extents(struct comp_target_swapchain *cts, VkExtent2D extent)
+{
+	VkExtent2D old = cts->override.extent;
+
+	COMP_INFO(                                                                  //
+	    cts->base.c,                                                            //
+	    "Target '%s' overrides compositor extents with (%ux%u) was (%ux%u %s)", //
+	    cts->base.name,                                                         //
+	    extent.width,                                                           //
+	    extent.height,                                                          //
+	    old.width,                                                              //
+	    old.height,                                                             //
+	    cts->override.compositor_extent ? "true" : "false");                    //
+
+	cts->override.compositor_extent = true;
+	cts->override.extent = extent;
+}
+
 void
 comp_target_swapchain_cleanup(struct comp_target_swapchain *cts)
 {
diff --git a/src/xrt/compositor/main/comp_target_swapchain.h b/src/xrt/compositor/main/comp_target_swapchain.h
index 7098fcab4..24ddb400e 100644
--- a/src/xrt/compositor/main/comp_target_swapchain.h
+++ b/src/xrt/compositor/main/comp_target_swapchain.h
@@ -47,6 +47,22 @@ struct comp_target_swapchain
 	//! Also works as a frame index.
 	int64_t current_frame_id;
 
+	struct
+	{
+		/*!
+		 * Should we ignore the compositor's preferred extents. Some
+		 * targets, like the direct mode ones, requires a particular
+		 * set of dimensions.
+		 */
+		bool compositor_extent;
+
+		/*!
+		 * The extents that a sub-class wants us to use,
+		 * see @p ignore_compositor_extent above.
+		 */
+		VkExtent2D extent;
+	} override;
+
 	struct
 	{
 		VkSwapchainKHR handle;
@@ -129,6 +145,17 @@ void
 comp_target_swapchain_init_and_set_fnptrs(struct comp_target_swapchain *cts,
                                           enum comp_target_display_timing_usage timing_usage);
 
+/*!
+ * Set that any size from the compositor should be ignored and that given size
+ * must be used for the @p VkSwapchain the helper code creates.
+ *
+ * @protected @memberof comp_target_swapchain
+ *
+ * @ingroup comp_main
+ */
+void
+comp_target_swapchain_override_extents(struct comp_target_swapchain *cts, VkExtent2D extent);
+
 /*!
  * Free all managed resources on the given @ref comp_target_swapchain,
  * does not free the struct itself.
diff --git a/src/xrt/compositor/main/comp_window_direct_nvidia.c b/src/xrt/compositor/main/comp_window_direct_nvidia.c
index 95c12335b..a65c27a2a 100644
--- a/src/xrt/compositor/main/comp_window_direct_nvidia.c
+++ b/src/xrt/compositor/main/comp_window_direct_nvidia.c
@@ -160,8 +160,7 @@ append_nvidia_entry_on_match(struct comp_window_direct_nvidia *w,
 	 */
 
 	// Make the compositor use this size.
-	w->base.base.c->settings.preferred.width = disp->physicalResolution.width;
-	w->base.base.c->settings.preferred.height = disp->physicalResolution.height;
+	comp_target_swapchain_override_extents(&w->base, disp->physicalResolution);
 
 	// Create the entry.
 	struct comp_window_direct_nvidia_display d = {
diff --git a/src/xrt/compositor/main/comp_window_direct_randr.c b/src/xrt/compositor/main/comp_window_direct_randr.c
index f6f9a727a..fc570467c 100644
--- a/src/xrt/compositor/main/comp_window_direct_randr.c
+++ b/src/xrt/compositor/main/comp_window_direct_randr.c
@@ -223,8 +223,8 @@ comp_window_direct_randr_init(struct comp_target *ct)
 	struct comp_window_direct_randr_display *d = comp_window_direct_randr_current_display(w_direct);
 
 	// Make the compositor use this size.
-	ct->c->settings.preferred.width = d->primary_mode.width;
-	ct->c->settings.preferred.height = d->primary_mode.height;
+	VkExtent2D extent = {d->primary_mode.width, d->primary_mode.height};
+	comp_target_swapchain_override_extents(&w_direct->base, extent);
 
 	return true;
 }
diff --git a/src/xrt/compositor/main/comp_window_vk_display.c b/src/xrt/compositor/main/comp_window_vk_display.c
index 01631b261..abc867394 100644
--- a/src/xrt/compositor/main/comp_window_vk_display.c
+++ b/src/xrt/compositor/main/comp_window_vk_display.c
@@ -128,8 +128,7 @@ static bool
 append_vk_display_entry(struct comp_window_vk_display *w, struct VkDisplayPropertiesKHR *disp)
 {
 	// Make the compositor use this size.
-	w->base.base.c->settings.preferred.width = disp->physicalResolution.width;
-	w->base.base.c->settings.preferred.height = disp->physicalResolution.height;
+	comp_target_swapchain_override_extents(&w->base, disp->physicalResolution);
 
 	// Create the entry.
 	struct vk_display d = {
diff --git a/src/xrt/compositor/main/comp_window_xcb.c b/src/xrt/compositor/main/comp_window_xcb.c
index a6bd31a97..3e643669d 100644
--- a/src/xrt/compositor/main/comp_window_xcb.c
+++ b/src/xrt/compositor/main/comp_window_xcb.c
@@ -90,7 +90,7 @@ static int
 comp_window_xcb_connect(struct comp_window_xcb *w);
 
 static void
-comp_window_xcb_create_window(struct comp_window_xcb *w, uint32_t width, uint32_t height);
+comp_window_xcb_create_window(struct comp_window_xcb *w, VkExtent2D extent);
 
 static void
 comp_window_xcb_get_randr_outputs(struct comp_window_xcb *w);
@@ -237,17 +237,23 @@ comp_window_xcb_init(struct comp_target *ct)
 		}
 
 		if (d->size.width != 0 && d->size.height != 0) {
-			ct->c->settings.preferred.width = d->size.width;
-			ct->c->settings.preferred.height = d->size.height;
 			COMP_DEBUG(ct->c, "Setting window size %dx%d.", d->size.width, d->size.height);
 
-			// TODO: size cb
-			// set_size_cb(settings->width, settings->height);
+			VkExtent2D extent = {d->size.width, d->size.height};
+			comp_target_swapchain_override_extents(&w_xcb->base, extent);
 		}
 	}
 
+	// The extent of the window we are about to create.
+	VkExtent2D extent = {ct->c->settings.preferred.width, ct->c->settings.preferred.height};
+
+	// If we require a particular size, use that.
+	if (w_xcb->base.override.compositor_extent) {
+		extent = w_xcb->base.override.extent;
+	}
+
 	// We can now create the window.
-	comp_window_xcb_create_window(w_xcb, ct->c->settings.preferred.width, ct->c->settings.preferred.height);
+	comp_window_xcb_create_window(w_xcb, extent);
 
 	comp_window_xcb_connect_delete_event(w_xcb);
 
@@ -294,7 +300,7 @@ comp_window_xcb_connect(struct comp_window_xcb *w)
 }
 
 static void
-comp_window_xcb_create_window(struct comp_window_xcb *w, uint32_t width, uint32_t height)
+comp_window_xcb_create_window(struct comp_window_xcb *w, VkExtent2D extent)
 {
 	w->window = xcb_generate_id(w->connection);
 
@@ -315,8 +321,8 @@ comp_window_xcb_create_window(struct comp_window_xcb *w, uint32_t width, uint32_
 	    w->screen->root,               // parent
 	    x,                             // x
 	    y,                             // y
-	    width,                         // width
-	    height,                        // height
+	    extent.width,                  // width
+	    extent.height,                 // height
 	    0,                             // border_width
 	    XCB_WINDOW_CLASS_INPUT_OUTPUT, // _class
 	    w->screen->root_visual,        // visual