diff --git a/backend/x11/output.c b/backend/x11/output.c
index 585e037a..58c90a89 100644
--- a/backend/x11/output.c
+++ b/backend/x11/output.c
@@ -63,6 +63,10 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output,
 	struct wlr_x11_output *output = get_x11_output_from_output(wlr_output);
 	struct wlr_x11_backend *x11 = output->x11;
 
+	if (width == output->win_width && height == output->win_height) {
+		return true;
+	}
+
 	const uint32_t values[] = { width, height };
 	xcb_void_cookie_t cookie = xcb_configure_window_checked(
 		x11->xcb, output->win,
@@ -76,6 +80,9 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output,
 		return false;
 	}
 
+	output->win_width = width;
+	output->win_height = height;
+
 	// Move the pointer to its new location
 	update_x11_pointer_position(output, output->x11->time);
 
@@ -598,6 +605,9 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend) {
 		x11->screen->root, 0, 0, wlr_output->width, wlr_output->height, 0,
 		XCB_WINDOW_CLASS_INPUT_OUTPUT, x11->visualid, mask, values);
 
+	output->win_width = wlr_output->width;
+	output->win_height = wlr_output->height;
+
 	struct {
 		xcb_input_event_mask_t head;
 		xcb_input_xi_event_mask_t mask;
@@ -659,6 +669,9 @@ void handle_x11_configure_notify(struct wlr_x11_output *output,
 		return;
 	}
 
+	output->win_width = ev->width;
+	output->win_height = ev->height;
+
 	struct wlr_output_state state;
 	wlr_output_state_init(&state);
 	wlr_output_state_set_custom_mode(&state, ev->width, ev->height, 0);
diff --git a/include/backend/x11.h b/include/backend/x11.h
index 06834c1c..9eb208b1 100644
--- a/include/backend/x11.h
+++ b/include/backend/x11.h
@@ -35,6 +35,8 @@ struct wlr_x11_output {
 	xcb_window_t win;
 	xcb_present_event_t present_event_id;
 
+	int32_t win_width, win_height;
+
 	struct wlr_pointer pointer;
 
 	struct wlr_touch touch;