diff --git a/src/cairo-xlib-private.h b/src/cairo-xlib-private.h
index 8e338aea6..e8900030b 100644
--- a/src/cairo-xlib-private.h
+++ b/src/cairo-xlib-private.h
@@ -83,7 +83,7 @@ struct _cairo_xlib_display {
 
     int render_major;
     int render_minor;
-    XRenderPictFormat *cached_xrender_formats[CAIRO_FORMAT_RGB30 + 1];
+    XRenderPictFormat *cached_xrender_formats[CAIRO_FORMAT_RGBA128F + 1];
 
     int force_precision;